diff --git a/.github/workflows/test-framework-php.yml b/.github/workflows/test-framework-php.yml
index 0b5e4b32745..e3dfebda70f 100644
--- a/.github/workflows/test-framework-php.yml
+++ b/.github/workflows/test-framework-php.yml
@@ -160,7 +160,7 @@ jobs:
       - name: Setup PHP with composer v2
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '7.4'
+          php-version: '8.3'
           tools: composer:v2
     ###############################################
     ##### END DYNAMIC: Dependent on build environment
diff --git a/.github/workflows/test-framework-v2-php.yml b/.github/workflows/test-framework-v2-php.yml
index af6a0e7083d..7c7e69da723 100644
--- a/.github/workflows/test-framework-v2-php.yml
+++ b/.github/workflows/test-framework-v2-php.yml
@@ -143,7 +143,7 @@ jobs:
       - name: Setup PHP with composer v2
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '7.4'
+          php-version: '8.3'
           tools: composer:v2
     ###############################################
     ##### END DYNAMIC: Dependent on build environment
diff --git a/.github/workflows/test-framework-v3-php.yml b/.github/workflows/test-framework-v3-php.yml
index ae871aba9cb..3954674e242 100644
--- a/.github/workflows/test-framework-v3-php.yml
+++ b/.github/workflows/test-framework-v3-php.yml
@@ -145,7 +145,7 @@ jobs:
       - name: Setup PHP with composer v2
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '7.4'
+          php-version: '8.3'
           tools: composer:v2
     ###############################################
     ##### END DYNAMIC: Dependent on build environment
diff --git a/.github/workflows/test-generation-v2.yml b/.github/workflows/test-generation-v2.yml
index 0185a2159c4..4825397a804 100644
--- a/.github/workflows/test-generation-v2.yml
+++ b/.github/workflows/test-generation-v2.yml
@@ -410,7 +410,7 @@ jobs:
       - name: Setup PHP with composer v2
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '7.4'
+          php-version: '8.3'
           tools: composer:v2
       ###############################################
       ##### END DYNAMIC: Dependent on build environment
diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java
index ffaed0e5e16..4fe7304f7ee 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java
@@ -316,7 +316,7 @@ public void processOpts() {
         supportingFiles.add(new SupportingFile("README.mustache", getPackagePath(), "README.md"));
         supportingFiles.add(new SupportingFile("phpunit.xml.mustache", getPackagePath(), "phpunit.xml.dist"));
         supportingFiles.add(new SupportingFile(".travis.yml", getPackagePath(), ".travis.yml"));
-        supportingFiles.add(new SupportingFile(".php_cs", getPackagePath(), ".php_cs"));
+        supportingFiles.add(new SupportingFile(".php-cs-fixer.php", getPackagePath(), ".php-cs-fixer.php"));
         supportingFiles.add(new SupportingFile("git_push.sh.mustache", getPackagePath(), "git_push.sh"));
     }
 
diff --git a/modules/swagger-codegen/src/main/resources/php-symfony/composer.mustache b/modules/swagger-codegen/src/main/resources/php-symfony/composer.mustache
index 5d6156df550..b9ef879091a 100644
--- a/modules/swagger-codegen/src/main/resources/php-symfony/composer.mustache
+++ b/modules/swagger-codegen/src/main/resources/php-symfony/composer.mustache
@@ -30,7 +30,7 @@
     "require-dev": {
         "phpunit/phpunit": "~4.8",
         "satooshi/php-coveralls": "~1.0",
-        "squizlabs/php_codesniffer": "~2.6",
+        "squizlabs/php_codesniffer": "^3.0",
         "friendsofphp/php-cs-fixer": "~1.12",
         "symfony/browser-kit": "*",
         "hoa/regex": "~1.0"
diff --git a/modules/swagger-codegen/src/main/resources/php/.php_cs b/modules/swagger-codegen/src/main/resources/php/.php-cs-fixer.php
similarity index 91%
rename from modules/swagger-codegen/src/main/resources/php/.php_cs
rename to modules/swagger-codegen/src/main/resources/php/.php-cs-fixer.php
index 4fbe53ec5ff..dc702622b95 100644
--- a/modules/swagger-codegen/src/main/resources/php/.php_cs
+++ b/modules/swagger-codegen/src/main/resources/php/.php-cs-fixer.php
@@ -1,7 +1,8 @@
 <?php
 
-return PhpCsFixer\Config::create()
+return (new PhpCsFixer\Config())
     ->setUsingCache(true)
+    ->setRiskyAllowed(true)
     ->setRules([
         '@PSR2' => true,
         'ordered_imports' => true,
diff --git a/modules/swagger-codegen/src/main/resources/php/.travis.yml b/modules/swagger-codegen/src/main/resources/php/.travis.yml
index d77f3825f6f..989be894218 100644
--- a/modules/swagger-codegen/src/main/resources/php/.travis.yml
+++ b/modules/swagger-codegen/src/main/resources/php/.travis.yml
@@ -1,10 +1,6 @@
 language: php
 sudo: false
 php:
-    - 5.4
-    - 5.5
-    - 5.6
-    - 7.0
-    - hhvm
+    - 8.3
 before_install: "composer install"
 script: "vendor/bin/phpunit"
diff --git a/modules/swagger-codegen/src/main/resources/php/README.mustache b/modules/swagger-codegen/src/main/resources/php/README.mustache
index 18bb80f7ce0..fea61dadffe 100644
--- a/modules/swagger-codegen/src/main/resources/php/README.mustache
+++ b/modules/swagger-codegen/src/main/resources/php/README.mustache
@@ -19,7 +19,7 @@ For more information, please visit [{{{infoUrl}}}]({{{infoUrl}}})
 
 ## Requirements
 
-PHP 5.5 and later
+PHP 8.3 and later
 
 ## Installation & Usage
 ### Composer
@@ -59,7 +59,7 @@ composer install
 ./vendor/bin/phpunit
 ```
 
-**Note:** Running tests requires PHP 7.2 or later, while the runtime library supports PHP 5.5 and later.
+**Note:** Running tests requires PHP 8.3 or later.
 
 ## Getting Started
 
diff --git a/modules/swagger-codegen/src/main/resources/php/api.mustache b/modules/swagger-codegen/src/main/resources/php/api.mustache
index e0b01e1f678..5b11cb3b1d1 100644
--- a/modules/swagger-codegen/src/main/resources/php/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/php/api.mustache
@@ -20,7 +20,8 @@ namespace {{apiPackage}};
 
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
+use GuzzleHttp\Exception\ResponseException;
+use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\Psr7\MultipartStream;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\RequestOptions;
@@ -60,9 +61,9 @@ use {{invokerPackage}}\ObjectSerializer;
      * @param HeaderSelector  $selector
      */
     public function __construct(
-        ClientInterface $client = null,
-        Configuration $config = null,
-        HeaderSelector $selector = null
+        ?ClientInterface $client = null,
+        ?Configuration $config = null,
+        ?HeaderSelector $selector = null
     ) {
         $this->client = $client ?: new Client();
         $this->config = $config ?: new Configuration();
@@ -93,8 +94,9 @@ use {{invokerPackage}}\ObjectSerializer;
      * @param  {{dataType}} ${{paramName}}{{#description}} {{description}}{{/description}}{{^description}} {{paramName}}{{/description}} {{#required}}(required){{/required}}{{^required}}(optional{{#defaultValue}}, default to {{{.}}}{{/defaultValue}}){{/required}}
 {{/allParams}}
      *
-     * @throws \{{invokerPackage}}\ApiException on non-2xx response
+     * @throws \{{invokerPackage}}\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return {{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}void{{/returnType}}
      */
     public function {{operationId}}({{#allParams}}${{paramName}}{{^required}} = {{#defaultValue}}'{{{.}}}'{{/defaultValue}}{{^defaultValue}}null{{/defaultValue}}{{/required}}{{#hasMore}}, {{/hasMore}}{{/allParams}})
@@ -118,8 +120,9 @@ use {{invokerPackage}}\ObjectSerializer;
      * @param  {{dataType}} ${{paramName}}{{#description}} {{description}}{{/description}} {{#required}}(required){{/required}}{{^required}}(optional{{#defaultValue}}, default to {{{.}}}{{/defaultValue}}){{/required}}
 {{/allParams}}
      *
-     * @throws \{{invokerPackage}}\ApiException on non-2xx response
+     * @throws \{{invokerPackage}}\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of {{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}null{{/returnType}}, HTTP status code, HTTP response headers (array of strings)
      */
     public function {{operationId}}WithHttpInfo({{#allParams}}${{paramName}}{{^required}} = {{#defaultValue}}'{{{.}}}'{{/defaultValue}}{{^defaultValue}}null{{/defaultValue}}{{/required}}{{#hasMore}}, {{/hasMore}}{{/allParams}})
@@ -131,13 +134,17 @@ use {{invokerPackage}}\ObjectSerializer;
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -209,6 +216,7 @@ use {{invokerPackage}}\ObjectSerializer;
 {{/allParams}}
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function {{operationId}}Async({{#allParams}}${{paramName}}{{^required}} = {{#defaultValue}}'{{{.}}}'{{/defaultValue}}{{^defaultValue}}null{{/defaultValue}}{{/required}}{{#hasMore}}, {{/hasMore}}{{/allParams}})
@@ -235,6 +243,7 @@ use {{invokerPackage}}\ObjectSerializer;
 {{/allParams}}
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function {{operationId}}AsyncWithHttpInfo({{#allParams}}${{paramName}}{{^required}} = {{#defaultValue}}'{{{.}}}'{{/defaultValue}}{{^defaultValue}}null{{/defaultValue}}{{/required}}{{#hasMore}}, {{/hasMore}}{{/allParams}})
@@ -268,17 +277,23 @@ use {{invokerPackage}}\ObjectSerializer;
                 {{/returnType}}
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -292,6 +307,7 @@ use {{invokerPackage}}\ObjectSerializer;
 {{/allParams}}
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function {{operationId}}Request({{#allParams}}${{paramName}}{{^required}} = {{#defaultValue}}'{{{.}}}'{{/defaultValue}}{{^defaultValue}}null{{/defaultValue}}{{/required}}{{#hasMore}}, {{/hasMore}}{{/allParams}})
@@ -396,7 +412,7 @@ use {{invokerPackage}}\ObjectSerializer;
         if (${{paramName}} !== null) {
             {{#isFile}}
             $multipart = true;
-            $formParams['{{baseName}}'] = \GuzzleHttp\Psr7\try_fopen(ObjectSerializer::toFormValue(${{paramName}}), 'rb');
+            $formParams['{{baseName}}'] = \GuzzleHttp\Psr7\Utils::tryFopen(ObjectSerializer::toFormValue(${{paramName}}), 'rb');
             {{/isFile}}
             {{^isFile}}
             $formParams['{{baseName}}'] = ObjectSerializer::toFormValue(${{paramName}});
@@ -430,11 +446,11 @@ use {{invokerPackage}}\ObjectSerializer;
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -450,7 +466,7 @@ use {{invokerPackage}}\ObjectSerializer;
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
diff --git a/modules/swagger-codegen/src/main/resources/php/composer.mustache b/modules/swagger-codegen/src/main/resources/php/composer.mustache
index 6f745a2c80d..c9b66bbb39c 100644
--- a/modules/swagger-codegen/src/main/resources/php/composer.mustache
+++ b/modules/swagger-codegen/src/main/resources/php/composer.mustache
@@ -19,16 +19,16 @@
         }
     ],
     "require": {
-        "php": ">=5.5",
+        "php": ">=8.3",
         "ext-curl": "*",
         "ext-json": "*",
         "ext-mbstring": "*",
-        "guzzlehttp/guzzle": "^6.2"
+        "guzzlehttp/guzzle": "^8.3"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.5.52",
-        "squizlabs/php_codesniffer": "~2.6",
-        "friendsofphp/php-cs-fixer": "~2.12"
+        "phpunit/phpunit": "^9.6",
+        "squizlabs/php_codesniffer": "^3.0",
+        "friendsofphp/php-cs-fixer": "^3.0"
     },
     "autoload": {
         "psr-4": { "{{escapedInvokerPackage}}\\" : "{{srcBasePath}}/" }
diff --git a/modules/swagger-generator/pom.xml b/modules/swagger-generator/pom.xml
index 3ec3339a39d..e87f75473b0 100644
--- a/modules/swagger-generator/pom.xml
+++ b/modules/swagger-generator/pom.xml
@@ -73,7 +73,7 @@
                     <webResources>
                         <resource>
                             <!-- this is relative to the pom.xml directory -->
-                            <directory>${project.build.directory}/swagger-ui-master/dist</directory>
+                            <directory>${project.build.directory}/swagger-ui-main/dist</directory>
                             <excludes>
                                 <exclude>index.html</exclude>
                             </excludes>
@@ -144,7 +144,7 @@
                             <goal>wget</goal>
                         </goals>
                         <configuration>
-                            <url>https://github.com/swagger-api/swagger-ui/archive/master.tar.gz</url>
+                            <url>https://github.com/swagger-api/swagger-ui/archive/main.tar.gz</url>
                             <unpack>true</unpack>
                             <outputDirectory>${project.build.directory}</outputDirectory>
                         </configuration>
diff --git a/samples/client/petstore-security-test/php/.swagger-codegen/VERSION b/samples/client/petstore-security-test/php/.swagger-codegen/VERSION
index 855ff9501eb..bab531eaf33 100644
--- a/samples/client/petstore-security-test/php/.swagger-codegen/VERSION
+++ b/samples/client/petstore-security-test/php/.swagger-codegen/VERSION
@@ -1 +1 @@
-2.4.0-SNAPSHOT
\ No newline at end of file
+2.4.53-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/php/SwaggerClient-php/.php_cs b/samples/client/petstore-security-test/php/SwaggerClient-php/.php-cs-fixer.php
similarity index 91%
rename from samples/client/petstore/php/SwaggerClient-php/.php_cs
rename to samples/client/petstore-security-test/php/SwaggerClient-php/.php-cs-fixer.php
index 4fbe53ec5ff..dc702622b95 100644
--- a/samples/client/petstore/php/SwaggerClient-php/.php_cs
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/.php-cs-fixer.php
@@ -1,7 +1,8 @@
 <?php
 
-return PhpCsFixer\Config::create()
+return (new PhpCsFixer\Config())
     ->setUsingCache(true)
+    ->setRiskyAllowed(true)
     ->setRules([
         '@PSR2' => true,
         'ordered_imports' => true,
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/.php_cs b/samples/client/petstore-security-test/php/SwaggerClient-php/.php_cs
deleted file mode 100644
index 6b8e23c818a..00000000000
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/.php_cs
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-
-return Symfony\CS\Config::create()
-    ->level(Symfony\CS\FixerInterface::PSR2_LEVEL)
-    ->setUsingCache(true)
-    ->fixers(
-        [
-            'ordered_use',
-            'phpdoc_order',
-            'short_array_syntax',
-            'strict',
-            'strict_param'
-        ]
-    )
-    ->finder(
-        Symfony\CS\Finder\DefaultFinder::create()
-            ->in(__DIR__)
-    );
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/.travis.yml b/samples/client/petstore-security-test/php/SwaggerClient-php/.travis.yml
index d77f3825f6f..989be894218 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/.travis.yml
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/.travis.yml
@@ -1,10 +1,6 @@
 language: php
 sudo: false
 php:
-    - 5.4
-    - 5.5
-    - 5.6
-    - 7.0
-    - hhvm
+    - 8.3
 before_install: "composer install"
 script: "vendor/bin/phpunit"
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/README.md b/samples/client/petstore-security-test/php/SwaggerClient-php/README.md
index 1f5c98d4da7..5c4b94e7d37 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/README.md
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/README.md
@@ -8,7 +8,7 @@ This PHP package is automatically generated by the [Swagger Codegen](https://git
 
 ## Requirements
 
-PHP 5.5 and later
+PHP 8.3 and later
 
 ## Installation & Usage
 ### Composer
@@ -48,6 +48,8 @@ composer install
 ./vendor/bin/phpunit
 ```
 
+**Note:** Running tests requires PHP 8.3 or later.
+
 ## Getting Started
 
 Please follow the [installation procedure](#installation--usage) and then run the following:
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/composer.json b/samples/client/petstore-security-test/php/SwaggerClient-php/composer.json
index 2ebbe805eea..86b5a5cd12b 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/composer.json
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/composer.json
@@ -16,16 +16,16 @@
         }
     ],
     "require": {
-        "php": ">=5.5",
+        "php": ">=8.3",
         "ext-curl": "*",
         "ext-json": "*",
         "ext-mbstring": "*",
-        "guzzlehttp/guzzle": "^6.2"
+        "guzzlehttp/guzzle": "^8.3"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.8",
-        "squizlabs/php_codesniffer": "~2.6",
-        "friendsofphp/php-cs-fixer": "~1.12"
+        "phpunit/phpunit": "^9.6",
+        "squizlabs/php_codesniffer": "^3.0",
+        "friendsofphp/php-cs-fixer": "^3.0"
     },
     "autoload": {
         "psr-4": { "Swagger\\Client\\" : "lib/" }
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/git_push.sh b/samples/client/petstore-security-test/php/SwaggerClient-php/git_push.sh
index 160f6f21399..ea15627ab9f 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/git_push.sh
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/git_push.sh
@@ -6,6 +6,7 @@
 git_user_id=$1
 git_repo_id=$2
 release_note=$3
+git_repo_base_url=$4
 
 if [ "$git_user_id" = "" ]; then
     git_user_id="GIT_USER_ID"
@@ -22,6 +23,11 @@ if [ "$release_note" = "" ]; then
     echo "[INFO] No command line input provided. Set \$release_note to $release_note"
 fi
 
+if [ "$git_repo_base_url" = "" ]; then
+    git_repo_base_url="https://github.com"
+    echo "[INFO] No command line input provided. Set \$git_repo_base_url to $git_repo_base_url"
+fi
+
 # Initialize the local directory as a Git repository
 git init
 
@@ -37,9 +43,11 @@ if [ "$git_remote" = "" ]; then # git remote not defined
 
     if [ "$GIT_TOKEN" = "" ]; then
         echo "[INFO] \$GIT_TOKEN (environment variable) is not set. Using the git credential in your environment."
-        git remote add origin https://github.com/${git_user_id}/${git_repo_id}.git
+        git remote add origin ${git_repo_base_url}/${git_user_id}/${git_repo_id}.git
     else
-        git remote add origin https://${git_user_id}:${GIT_TOKEN}@github.com/${git_user_id}/${git_repo_id}.git
+        git_repo_base_url=${git_repo_base_url#*//}
+        git_repo_base_url=${git_repo_base_url%%.*}
+        git remote add origin https://${git_user_id}:${GIT_TOKEN}@${git_repo_base_url}.com/${git_user_id}/${git_repo_id}.git
     fi
 
 fi
@@ -47,6 +55,6 @@ fi
 git pull origin master
 
 # Pushes (Forces) the changes in the local repository up to the remote repository
-echo "Git pushing to https://github.com/${git_user_id}/${git_repo_id}.git"
+echo "Git pushing to https://${git_repo_base_url}.com/${git_user_id}/${git_repo_id}.git"
 git push origin master 2>&1 | grep -v 'To https'
 
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Api/FakeApi.php b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Api/FakeApi.php
index 5f2eb0eff73..52c61afff2b 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Api/FakeApi.php
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Api/FakeApi.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0 *_/ ' \" =end -- \\r\\n \\n \\r
  * Contact: apiteam@swagger.io *_/ ' \" =end -- \\r\\n \\n \\r
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.0-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -30,7 +30,8 @@
 
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
+use GuzzleHttp\Exception\ResponseException;
+use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\Psr7\MultipartStream;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\RequestOptions;
@@ -70,9 +71,9 @@ class FakeApi
      * @param HeaderSelector  $selector
      */
     public function __construct(
-        ClientInterface $client = null,
-        Configuration $config = null,
-        HeaderSelector $selector = null
+        ?ClientInterface $client = null,
+        ?Configuration $config = null,
+        ?HeaderSelector $selector = null
     ) {
         $this->client = $client ?: new Client();
         $this->config = $config ?: new Configuration();
@@ -94,8 +95,9 @@ public function getConfig()
      *
      * @param  string $test_code_inject____end____rn_n_r To test code injection *_/ &#39; \&quot; &#x3D;end -- \\r\\n \\n \\r (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function testCodeInjectEndRnNR($test_code_inject____end____rn_n_r = null)
@@ -110,8 +112,9 @@ public function testCodeInjectEndRnNR($test_code_inject____end____rn_n_r = null)
      *
      * @param  string $test_code_inject____end____rn_n_r To test code injection *_/ &#39; \&quot; &#x3D;end -- \\r\\n \\n \\r (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function testCodeInjectEndRnNRWithHttpInfo($test_code_inject____end____rn_n_r = null)
@@ -123,13 +126,17 @@ public function testCodeInjectEndRnNRWithHttpInfo($test_code_inject____end____rn
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -164,6 +171,7 @@ public function testCodeInjectEndRnNRWithHttpInfo($test_code_inject____end____rn
      * @param  string $test_code_inject____end____rn_n_r To test code injection *_/ &#39; \&quot; &#x3D;end -- \\r\\n \\n \\r (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testCodeInjectEndRnNRAsync($test_code_inject____end____rn_n_r = null)
@@ -184,6 +192,7 @@ function ($response) {
      * @param  string $test_code_inject____end____rn_n_r To test code injection *_/ &#39; \&quot; &#x3D;end -- \\r\\n \\n \\r (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testCodeInjectEndRnNRAsyncWithHttpInfo($test_code_inject____end____rn_n_r = null)
@@ -198,17 +207,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -220,6 +235,7 @@ function ($exception) {
      * @param  string $test_code_inject____end____rn_n_r To test code injection *_/ &#39; \&quot; &#x3D;end -- \\r\\n \\n \\r (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function testCodeInjectEndRnNRRequest($test_code_inject____end____rn_n_r = null)
@@ -256,9 +272,16 @@ protected function testCodeInjectEndRnNRRequest($test_code_inject____end____rn_n
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -273,7 +296,7 @@ protected function testCodeInjectEndRnNRRequest($test_code_inject____end____rn_n
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/ApiException.php b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/ApiException.php
index 9ed326a3c6f..df4ede95c14 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/ApiException.php
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/ApiException.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0 *_/ ' \" =end -- \\r\\n \\n \\r
  * Contact: apiteam@swagger.io *_/ ' \" =end -- \\r\\n \\n \\r
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.0-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Configuration.php b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Configuration.php
index 192e8b2c6c7..7977daf0e1a 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Configuration.php
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Configuration.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0 *_/ ' \" =end -- \\r\\n \\n \\r
  * Contact: apiteam@swagger.io *_/ ' \" =end -- \\r\\n \\n \\r
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.0-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/HeaderSelector.php b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/HeaderSelector.php
index 676173de468..a19fc4e2eeb 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/HeaderSelector.php
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/HeaderSelector.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0 *_/ ' \" =end -- \\r\\n \\n \\r
  * Contact: apiteam@swagger.io *_/ ' \" =end -- \\r\\n \\n \\r
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.0-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -107,4 +107,3 @@ private function selectContentTypeHeader($contentType)
         }
     }
 }
-
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Model/ModelInterface.php b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Model/ModelInterface.php
index 6013c8cf977..2232a898a2e 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Model/ModelInterface.php
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Model/ModelInterface.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0 *_/ ' \" =end -- \\r\\n \\n \\r
  * Contact: apiteam@swagger.io *_/ ' \" =end -- \\r\\n \\n \\r
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.0-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Model/ModelReturn.php b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Model/ModelReturn.php
index 4d820c4cc87..ec1e50639ca 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Model/ModelReturn.php
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/Model/ModelReturn.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0 *_/ ' \" =end -- \\r\\n \\n \\r
  * Contact: apiteam@swagger.io *_/ ' \" =end -- \\r\\n \\n \\r
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.0-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -235,6 +235,7 @@ public function setReturn($return)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -247,6 +248,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -260,6 +262,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -276,6 +279,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/ObjectSerializer.php b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/ObjectSerializer.php
index 720eb97a8e5..85d32a9d239 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/lib/ObjectSerializer.php
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/lib/ObjectSerializer.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0 *_/ ' \" =end -- \\r\\n \\n \\r
  * Contact: apiteam@swagger.io *_/ ' \" =end -- \\r\\n \\n \\r
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.0-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -59,6 +59,11 @@ public static function sanitizeForSerialization($data, $type = null, $format = n
                 $data[$property] = self::sanitizeForSerialization($value);
             }
             return $data;
+        } elseif ($data instanceof \stdClass) {
+            foreach ($data as $property => $value) {
+                $data->$property = self::sanitizeForSerialization($value);
+            }
+            return $data;
         } elseif (is_object($data)) {
             $values = [];
             $formats = $data::swaggerFormats();
@@ -68,7 +73,7 @@ public static function sanitizeForSerialization($data, $type = null, $format = n
                 if ($value !== null
                     && !in_array($swaggerType, ['DateTime', 'bool', 'boolean', 'byte', 'double', 'float', 'int', 'integer', 'mixed', 'number', 'object', 'string', 'void'], true)
                     && method_exists($swaggerType, 'getAllowableEnumValues')
-                    && !in_array($value, $swaggerType::getAllowableEnumValues())) {
+                    && !in_array($value, $swaggerType::getAllowableEnumValues(), true)) {
                     $imploded = implode("', '", $swaggerType::getAllowableEnumValues());
                     throw new \InvalidArgumentException("Invalid value for enum '$swaggerType', must be one of: '$imploded'");
                 }
@@ -284,7 +289,7 @@ public static function deserialize($data, $class, $httpHeaders = null)
 
             return new \SplFileObject($filename, 'r');
         } elseif (method_exists($class, 'getAllowableEnumValues')) {
-            if (!in_array($data, $class::getAllowableEnumValues())) {
+            if (!in_array($data, $class::getAllowableEnumValues(), true)) {
                 $imploded = implode("', '", $class::getAllowableEnumValues());
                 throw new \InvalidArgumentException("Invalid value for enum '$class', must be one of: '$imploded'");
             }
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/test/Api/FakeApiTest.php b/samples/client/petstore-security-test/php/SwaggerClient-php/test/Api/FakeApiTest.php
index 613e83d2089..f51f3f469b6 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/test/Api/FakeApiTest.php
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/test/Api/FakeApiTest.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0 *_/ ' \" =end -- \\r\\n \\n \\r
  * Contact: apiteam@swagger.io *_/ ' \" =end -- \\r\\n \\n \\r
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.0-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -40,34 +40,34 @@
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
  */
-class FakeApiTest extends \PHPUnit_Framework_TestCase
+class FakeApiTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test cases
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore-security-test/php/SwaggerClient-php/test/Model/ModelReturnTest.php b/samples/client/petstore-security-test/php/SwaggerClient-php/test/Model/ModelReturnTest.php
index b49dc30a4e0..8543abdcf08 100644
--- a/samples/client/petstore-security-test/php/SwaggerClient-php/test/Model/ModelReturnTest.php
+++ b/samples/client/petstore-security-test/php/SwaggerClient-php/test/Model/ModelReturnTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0 *_/ ' \" =end -- \\r\\n \\n \\r
  * Contact: apiteam@swagger.io *_/ ' \" =end -- \\r\\n \\n \\r
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.0-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ModelReturnTest extends \PHPUnit_Framework_TestCase
+class ModelReturnTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/.swagger-codegen/VERSION b/samples/client/petstore/php/.swagger-codegen/VERSION
index 017674fb59d..bab531eaf33 100644
--- a/samples/client/petstore/php/.swagger-codegen/VERSION
+++ b/samples/client/petstore/php/.swagger-codegen/VERSION
@@ -1 +1 @@
-2.4.3-SNAPSHOT
\ No newline at end of file
+2.4.53-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/php/SwaggerClient-php/.php-cs-fixer.php b/samples/client/petstore/php/SwaggerClient-php/.php-cs-fixer.php
new file mode 100644
index 00000000000..dc702622b95
--- /dev/null
+++ b/samples/client/petstore/php/SwaggerClient-php/.php-cs-fixer.php
@@ -0,0 +1,24 @@
+<?php
+
+return (new PhpCsFixer\Config())
+    ->setUsingCache(true)
+    ->setRiskyAllowed(true)
+    ->setRules([
+        '@PSR2' => true,
+        'ordered_imports' => true,
+        'phpdoc_order' => true,
+        'array_syntax' => [ 'syntax' => 'short' ],
+        'strict_comparison' => true,
+        'strict_param' => true,
+        'no_trailing_whitespace' => false,
+        'no_trailing_whitespace_in_comment' => false,
+        'braces' => false,
+        'single_blank_line_at_eof' => false,
+        'blank_line_after_namespace' => false,
+    ])
+    ->setFinder(
+        PhpCsFixer\Finder::create()
+        ->exclude('test')
+        ->exclude('tests')
+        ->in(__DIR__)
+    );
diff --git a/samples/client/petstore/php/SwaggerClient-php/.travis.yml b/samples/client/petstore/php/SwaggerClient-php/.travis.yml
index d77f3825f6f..989be894218 100644
--- a/samples/client/petstore/php/SwaggerClient-php/.travis.yml
+++ b/samples/client/petstore/php/SwaggerClient-php/.travis.yml
@@ -1,10 +1,6 @@
 language: php
 sudo: false
 php:
-    - 5.4
-    - 5.5
-    - 5.6
-    - 7.0
-    - hhvm
+    - 8.3
 before_install: "composer install"
 script: "vendor/bin/phpunit"
diff --git a/samples/client/petstore/php/SwaggerClient-php/README.md b/samples/client/petstore/php/SwaggerClient-php/README.md
index feba5d37b72..1267a0ff3ef 100644
--- a/samples/client/petstore/php/SwaggerClient-php/README.md
+++ b/samples/client/petstore/php/SwaggerClient-php/README.md
@@ -1,5 +1,5 @@
 # SwaggerClient-php
-This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
 
 This PHP package is automatically generated by the [Swagger Codegen](https://github.com/swagger-api/swagger-codegen) project:
 
@@ -8,7 +8,7 @@ This PHP package is automatically generated by the [Swagger Codegen](https://git
 
 ## Requirements
 
-PHP 5.5 and later
+PHP 8.3 and later
 
 ## Installation & Usage
 ### Composer
@@ -48,6 +48,8 @@ composer install
 ./vendor/bin/phpunit
 ```
 
+**Note:** Running tests requires PHP 8.3 or later.
+
 ## Getting Started
 
 Please follow the [installation procedure](#installation--usage) and then run the following:
@@ -56,21 +58,18 @@ Please follow the [installation procedure](#installation--usage) and then run th
 <?php
 require_once(__DIR__ . '/vendor/autoload.php');
 
-// Configure OAuth2 access token for authorization: petstore_auth
-$config = Swagger\Client\Configuration::getDefaultConfiguration()->setAccessToken('YOUR_ACCESS_TOKEN');
-
-$apiInstance = new Swagger\Client\Api\PetApi(
+$apiInstance = new Swagger\Client\Api\AnotherFakeApi(
     // If you want use custom http client, pass your client which implements `GuzzleHttp\ClientInterface`.
     // This is optional, `GuzzleHttp\Client` will be used as default.
-    new GuzzleHttp\Client(),
-    $config
+    new GuzzleHttp\Client()
 );
-$body = new \Swagger\Client\Model\Pet(); // \Swagger\Client\Model\Pet | Pet object that needs to be added to the store
+$body = new \Swagger\Client\Model\Client(); // \Swagger\Client\Model\Client | client model
 
 try {
-    $apiInstance->addPet($body);
+    $result = $apiInstance->testSpecialTags($body);
+    print_r($result);
 } catch (Exception $e) {
-    echo 'Exception when calling PetApi->addPet: ', $e->getMessage(), PHP_EOL;
+    echo 'Exception when calling AnotherFakeApi->testSpecialTags: ', $e->getMessage(), PHP_EOL;
 }
 
 ?>
@@ -78,10 +77,22 @@ try {
 
 ## Documentation for API Endpoints
 
-All URIs are relative to *http://petstore.swagger.io/v2*
+All URIs are relative to *http://petstore.swagger.io:80/v2*
 
 Class | Method | HTTP request | Description
 ------------ | ------------- | ------------- | -------------
+*AnotherFakeApi* | [**testSpecialTags**](docs/Api/AnotherFakeApi.md#testspecialtags) | **PATCH** /another-fake/dummy | To test special tags
+*FakeApi* | [**fakeOuterBooleanSerialize**](docs/Api/FakeApi.md#fakeouterbooleanserialize) | **POST** /fake/outer/boolean | 
+*FakeApi* | [**fakeOuterCompositeSerialize**](docs/Api/FakeApi.md#fakeoutercompositeserialize) | **POST** /fake/outer/composite | 
+*FakeApi* | [**fakeOuterNumberSerialize**](docs/Api/FakeApi.md#fakeouternumberserialize) | **POST** /fake/outer/number | 
+*FakeApi* | [**fakeOuterStringSerialize**](docs/Api/FakeApi.md#fakeouterstringserialize) | **POST** /fake/outer/string | 
+*FakeApi* | [**testBodyWithQueryParams**](docs/Api/FakeApi.md#testbodywithqueryparams) | **PUT** /fake/body-with-query-params | 
+*FakeApi* | [**testClientModel**](docs/Api/FakeApi.md#testclientmodel) | **PATCH** /fake | To test \&quot;client\&quot; model
+*FakeApi* | [**testEndpointParameters**](docs/Api/FakeApi.md#testendpointparameters) | **POST** /fake | Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트
+*FakeApi* | [**testEnumParameters**](docs/Api/FakeApi.md#testenumparameters) | **GET** /fake | To test enum parameters
+*FakeApi* | [**testInlineAdditionalProperties**](docs/Api/FakeApi.md#testinlineadditionalproperties) | **POST** /fake/inline-additionalProperties | test inline additionalProperties
+*FakeApi* | [**testJsonFormData**](docs/Api/FakeApi.md#testjsonformdata) | **GET** /fake/jsonFormData | test json serialization of form data
+*FakeClassnameTags123Api* | [**testClassname**](docs/Api/FakeClassnameTags123Api.md#testclassname) | **PATCH** /fake_classname_test | To test class name in snake case
 *PetApi* | [**addPet**](docs/Api/PetApi.md#addpet) | **POST** /pet | Add a new pet to the store
 *PetApi* | [**deletePet**](docs/Api/PetApi.md#deletepet) | **DELETE** /pet/{petId} | Deletes a pet
 *PetApi* | [**findPetsByStatus**](docs/Api/PetApi.md#findpetsbystatus) | **GET** /pet/findByStatus | Finds Pets by status
@@ -90,9 +101,9 @@ Class | Method | HTTP request | Description
 *PetApi* | [**updatePet**](docs/Api/PetApi.md#updatepet) | **PUT** /pet | Update an existing pet
 *PetApi* | [**updatePetWithForm**](docs/Api/PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
 *PetApi* | [**uploadFile**](docs/Api/PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
-*StoreApi* | [**deleteOrder**](docs/Api/StoreApi.md#deleteorder) | **DELETE** /store/order/{orderId} | Delete purchase order by ID
+*StoreApi* | [**deleteOrder**](docs/Api/StoreApi.md#deleteorder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 *StoreApi* | [**getInventory**](docs/Api/StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
-*StoreApi* | [**getOrderById**](docs/Api/StoreApi.md#getorderbyid) | **GET** /store/order/{orderId} | Find purchase order by ID
+*StoreApi* | [**getOrderById**](docs/Api/StoreApi.md#getorderbyid) | **GET** /store/order/{order_id} | Find purchase order by ID
 *StoreApi* | [**placeOrder**](docs/Api/StoreApi.md#placeorder) | **POST** /store/order | Place an order for a pet
 *UserApi* | [**createUser**](docs/Api/UserApi.md#createuser) | **POST** /user | Create user
 *UserApi* | [**createUsersWithArrayInput**](docs/Api/UserApi.md#createuserswitharrayinput) | **POST** /user/createWithArray | Creates list of users with given input array
@@ -106,10 +117,41 @@ Class | Method | HTTP request | Description
 
 ## Documentation For Models
 
+ - [AdditionalPropertiesClass](docs/Model/AdditionalPropertiesClass.md)
+ - [Animal](docs/Model/Animal.md)
+ - [AnimalFarm](docs/Model/AnimalFarm.md)
  - [ApiResponse](docs/Model/ApiResponse.md)
+ - [ArrayOfArrayOfNumberOnly](docs/Model/ArrayOfArrayOfNumberOnly.md)
+ - [ArrayOfNumberOnly](docs/Model/ArrayOfNumberOnly.md)
+ - [ArrayTest](docs/Model/ArrayTest.md)
+ - [Boolean](docs/Model/Boolean.md)
+ - [Capitalization](docs/Model/Capitalization.md)
+ - [Cat](docs/Model/Cat.md)
  - [Category](docs/Model/Category.md)
+ - [ClassModel](docs/Model/ClassModel.md)
+ - [Client](docs/Model/Client.md)
+ - [Dog](docs/Model/Dog.md)
+ - [EnumArrays](docs/Model/EnumArrays.md)
+ - [EnumClass](docs/Model/EnumClass.md)
+ - [EnumTest](docs/Model/EnumTest.md)
+ - [FormatTest](docs/Model/FormatTest.md)
+ - [HasOnlyReadOnly](docs/Model/HasOnlyReadOnly.md)
+ - [MapTest](docs/Model/MapTest.md)
+ - [MixedPropertiesAndAdditionalPropertiesClass](docs/Model/MixedPropertiesAndAdditionalPropertiesClass.md)
+ - [Model200Response](docs/Model/Model200Response.md)
+ - [ModelList](docs/Model/ModelList.md)
+ - [ModelReturn](docs/Model/ModelReturn.md)
+ - [Name](docs/Model/Name.md)
+ - [NumberOnly](docs/Model/NumberOnly.md)
  - [Order](docs/Model/Order.md)
+ - [OuterBoolean](docs/Model/OuterBoolean.md)
+ - [OuterComposite](docs/Model/OuterComposite.md)
+ - [OuterEnum](docs/Model/OuterEnum.md)
+ - [OuterNumber](docs/Model/OuterNumber.md)
+ - [OuterString](docs/Model/OuterString.md)
  - [Pet](docs/Model/Pet.md)
+ - [ReadOnlyFirst](docs/Model/ReadOnlyFirst.md)
+ - [SpecialModelName](docs/Model/SpecialModelName.md)
  - [Tag](docs/Model/Tag.md)
  - [User](docs/Model/User.md)
 
@@ -123,6 +165,16 @@ Class | Method | HTTP request | Description
 - **API key parameter name**: api_key
 - **Location**: HTTP header
 
+## api_key_query
+
+- **Type**: API key
+- **API key parameter name**: api_key_query
+- **Location**: URL query string
+
+## http_basic_test
+
+- **Type**: HTTP basic authentication
+
 ## petstore_auth
 
 - **Type**: OAuth
diff --git a/samples/client/petstore/php/SwaggerClient-php/composer.json b/samples/client/petstore/php/SwaggerClient-php/composer.json
index 2d76f02819b..86b5a5cd12b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/composer.json
+++ b/samples/client/petstore/php/SwaggerClient-php/composer.json
@@ -16,16 +16,16 @@
         }
     ],
     "require": {
-        "php": ">=5.5",
+        "php": ">=8.3",
         "ext-curl": "*",
         "ext-json": "*",
         "ext-mbstring": "*",
-        "guzzlehttp/guzzle": "^6.2"
+        "guzzlehttp/guzzle": "^8.3"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.8",
-        "squizlabs/php_codesniffer": "~2.6",
-        "friendsofphp/php-cs-fixer": "~2.12"
+        "phpunit/phpunit": "^9.6",
+        "squizlabs/php_codesniffer": "^3.0",
+        "friendsofphp/php-cs-fixer": "^3.0"
     },
     "autoload": {
         "psr-4": { "Swagger\\Client\\" : "lib/" }
diff --git a/samples/client/petstore/php/SwaggerClient-php/docs/Api/PetApi.md b/samples/client/petstore/php/SwaggerClient-php/docs/Api/PetApi.md
index 6a1773d4b28..46e42007fac 100644
--- a/samples/client/petstore/php/SwaggerClient-php/docs/Api/PetApi.md
+++ b/samples/client/petstore/php/SwaggerClient-php/docs/Api/PetApi.md
@@ -1,6 +1,6 @@
 # Swagger\Client\PetApi
 
-All URIs are relative to *http://petstore.swagger.io/v2*
+All URIs are relative to *http://petstore.swagger.io:80/v2*
 
 Method | HTTP request | Description
 ------------- | ------------- | -------------
diff --git a/samples/client/petstore/php/SwaggerClient-php/docs/Api/StoreApi.md b/samples/client/petstore/php/SwaggerClient-php/docs/Api/StoreApi.md
index 649dcc4b265..87cec61aa7b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/docs/Api/StoreApi.md
+++ b/samples/client/petstore/php/SwaggerClient-php/docs/Api/StoreApi.md
@@ -1,12 +1,12 @@
 # Swagger\Client\StoreApi
 
-All URIs are relative to *http://petstore.swagger.io/v2*
+All URIs are relative to *http://petstore.swagger.io:80/v2*
 
 Method | HTTP request | Description
 ------------- | ------------- | -------------
-[**deleteOrder**](StoreApi.md#deleteOrder) | **DELETE** /store/order/{orderId} | Delete purchase order by ID
+[**deleteOrder**](StoreApi.md#deleteOrder) | **DELETE** /store/order/{order_id} | Delete purchase order by ID
 [**getInventory**](StoreApi.md#getInventory) | **GET** /store/inventory | Returns pet inventories by status
-[**getOrderById**](StoreApi.md#getOrderById) | **GET** /store/order/{orderId} | Find purchase order by ID
+[**getOrderById**](StoreApi.md#getOrderById) | **GET** /store/order/{order_id} | Find purchase order by ID
 [**placeOrder**](StoreApi.md#placeOrder) | **POST** /store/order | Place an order for a pet
 
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/docs/Api/UserApi.md b/samples/client/petstore/php/SwaggerClient-php/docs/Api/UserApi.md
index 7953ca871f6..52b0a351904 100644
--- a/samples/client/petstore/php/SwaggerClient-php/docs/Api/UserApi.md
+++ b/samples/client/petstore/php/SwaggerClient-php/docs/Api/UserApi.md
@@ -1,6 +1,6 @@
 # Swagger\Client\UserApi
 
-All URIs are relative to *http://petstore.swagger.io/v2*
+All URIs are relative to *http://petstore.swagger.io:80/v2*
 
 Method | HTTP request | Description
 ------------- | ------------- | -------------
diff --git a/samples/client/petstore/php/SwaggerClient-php/docs/Model/Boolean.md b/samples/client/petstore/php/SwaggerClient-php/docs/Model/Boolean.md
new file mode 100644
index 00000000000..d0b536f8086
--- /dev/null
+++ b/samples/client/petstore/php/SwaggerClient-php/docs/Model/Boolean.md
@@ -0,0 +1,9 @@
+# Boolean
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+
+[[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
+
+
diff --git a/samples/client/petstore/php/SwaggerClient-php/git_push.sh b/samples/client/petstore/php/SwaggerClient-php/git_push.sh
index 160f6f21399..ea15627ab9f 100644
--- a/samples/client/petstore/php/SwaggerClient-php/git_push.sh
+++ b/samples/client/petstore/php/SwaggerClient-php/git_push.sh
@@ -6,6 +6,7 @@
 git_user_id=$1
 git_repo_id=$2
 release_note=$3
+git_repo_base_url=$4
 
 if [ "$git_user_id" = "" ]; then
     git_user_id="GIT_USER_ID"
@@ -22,6 +23,11 @@ if [ "$release_note" = "" ]; then
     echo "[INFO] No command line input provided. Set \$release_note to $release_note"
 fi
 
+if [ "$git_repo_base_url" = "" ]; then
+    git_repo_base_url="https://github.com"
+    echo "[INFO] No command line input provided. Set \$git_repo_base_url to $git_repo_base_url"
+fi
+
 # Initialize the local directory as a Git repository
 git init
 
@@ -37,9 +43,11 @@ if [ "$git_remote" = "" ]; then # git remote not defined
 
     if [ "$GIT_TOKEN" = "" ]; then
         echo "[INFO] \$GIT_TOKEN (environment variable) is not set. Using the git credential in your environment."
-        git remote add origin https://github.com/${git_user_id}/${git_repo_id}.git
+        git remote add origin ${git_repo_base_url}/${git_user_id}/${git_repo_id}.git
     else
-        git remote add origin https://${git_user_id}:${GIT_TOKEN}@github.com/${git_user_id}/${git_repo_id}.git
+        git_repo_base_url=${git_repo_base_url#*//}
+        git_repo_base_url=${git_repo_base_url%%.*}
+        git remote add origin https://${git_user_id}:${GIT_TOKEN}@${git_repo_base_url}.com/${git_user_id}/${git_repo_id}.git
     fi
 
 fi
@@ -47,6 +55,6 @@ fi
 git pull origin master
 
 # Pushes (Forces) the changes in the local repository up to the remote repository
-echo "Git pushing to https://github.com/${git_user_id}/${git_repo_id}.git"
+echo "Git pushing to https://${git_repo_base_url}.com/${git_user_id}/${git_repo_id}.git"
 git push origin master 2>&1 | grep -v 'To https'
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Api/AnotherFakeApi.php b/samples/client/petstore/php/SwaggerClient-php/lib/Api/AnotherFakeApi.php
index c54892b41b3..f4ccb16b2f9 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Api/AnotherFakeApi.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Api/AnotherFakeApi.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -30,7 +30,8 @@
 
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
+use GuzzleHttp\Exception\ResponseException;
+use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\Psr7\MultipartStream;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\RequestOptions;
@@ -70,9 +71,9 @@ class AnotherFakeApi
      * @param HeaderSelector  $selector
      */
     public function __construct(
-        ClientInterface $client = null,
-        Configuration $config = null,
-        HeaderSelector $selector = null
+        ?ClientInterface $client = null,
+        ?Configuration $config = null,
+        ?HeaderSelector $selector = null
     ) {
         $this->client = $client ?: new Client();
         $this->config = $config ?: new Configuration();
@@ -94,8 +95,9 @@ public function getConfig()
      *
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\Client
      */
     public function testSpecialTags($body)
@@ -111,8 +113,9 @@ public function testSpecialTags($body)
      *
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\Client, HTTP status code, HTTP response headers (array of strings)
      */
     public function testSpecialTagsWithHttpInfo($body)
@@ -124,13 +127,17 @@ public function testSpecialTagsWithHttpInfo($body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -187,6 +194,7 @@ public function testSpecialTagsWithHttpInfo($body)
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testSpecialTagsAsync($body)
@@ -207,6 +215,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testSpecialTagsAsyncWithHttpInfo($body)
@@ -235,17 +244,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -257,6 +272,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function testSpecialTagsRequest($body)
@@ -298,9 +314,16 @@ protected function testSpecialTagsRequest($body)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -315,7 +338,7 @@ protected function testSpecialTagsRequest($body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeApi.php b/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeApi.php
index db1172f6ccc..c479a8e2fd2 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeApi.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeApi.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -30,7 +30,8 @@
 
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
+use GuzzleHttp\Exception\ResponseException;
+use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\Psr7\MultipartStream;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\RequestOptions;
@@ -70,9 +71,9 @@ class FakeApi
      * @param HeaderSelector  $selector
      */
     public function __construct(
-        ClientInterface $client = null,
-        Configuration $config = null,
-        HeaderSelector $selector = null
+        ?ClientInterface $client = null,
+        ?Configuration $config = null,
+        ?HeaderSelector $selector = null
     ) {
         $this->client = $client ?: new Client();
         $this->config = $config ?: new Configuration();
@@ -92,8 +93,9 @@ public function getConfig()
      *
      * @param  \Swagger\Client\Model\OuterBoolean $body Input boolean as post body (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\OuterBoolean
      */
     public function fakeOuterBooleanSerialize($body = null)
@@ -107,8 +109,9 @@ public function fakeOuterBooleanSerialize($body = null)
      *
      * @param  \Swagger\Client\Model\OuterBoolean $body Input boolean as post body (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\OuterBoolean, HTTP status code, HTTP response headers (array of strings)
      */
     public function fakeOuterBooleanSerializeWithHttpInfo($body = null)
@@ -120,13 +123,17 @@ public function fakeOuterBooleanSerializeWithHttpInfo($body = null)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -183,6 +190,7 @@ public function fakeOuterBooleanSerializeWithHttpInfo($body = null)
      * @param  \Swagger\Client\Model\OuterBoolean $body Input boolean as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function fakeOuterBooleanSerializeAsync($body = null)
@@ -203,6 +211,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\OuterBoolean $body Input boolean as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function fakeOuterBooleanSerializeAsyncWithHttpInfo($body = null)
@@ -231,17 +240,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -253,6 +268,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\OuterBoolean $body Input boolean as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function fakeOuterBooleanSerializeRequest($body = null)
@@ -288,9 +304,16 @@ protected function fakeOuterBooleanSerializeRequest($body = null)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -305,7 +328,7 @@ protected function fakeOuterBooleanSerializeRequest($body = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -339,8 +362,9 @@ protected function fakeOuterBooleanSerializeRequest($body = null)
      *
      * @param  \Swagger\Client\Model\OuterComposite $body Input composite as post body (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\OuterComposite
      */
     public function fakeOuterCompositeSerialize($body = null)
@@ -354,8 +378,9 @@ public function fakeOuterCompositeSerialize($body = null)
      *
      * @param  \Swagger\Client\Model\OuterComposite $body Input composite as post body (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\OuterComposite, HTTP status code, HTTP response headers (array of strings)
      */
     public function fakeOuterCompositeSerializeWithHttpInfo($body = null)
@@ -367,13 +392,17 @@ public function fakeOuterCompositeSerializeWithHttpInfo($body = null)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -430,6 +459,7 @@ public function fakeOuterCompositeSerializeWithHttpInfo($body = null)
      * @param  \Swagger\Client\Model\OuterComposite $body Input composite as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function fakeOuterCompositeSerializeAsync($body = null)
@@ -450,6 +480,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\OuterComposite $body Input composite as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function fakeOuterCompositeSerializeAsyncWithHttpInfo($body = null)
@@ -478,17 +509,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -500,6 +537,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\OuterComposite $body Input composite as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function fakeOuterCompositeSerializeRequest($body = null)
@@ -535,9 +573,16 @@ protected function fakeOuterCompositeSerializeRequest($body = null)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -552,7 +597,7 @@ protected function fakeOuterCompositeSerializeRequest($body = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -586,8 +631,9 @@ protected function fakeOuterCompositeSerializeRequest($body = null)
      *
      * @param  \Swagger\Client\Model\OuterNumber $body Input number as post body (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\OuterNumber
      */
     public function fakeOuterNumberSerialize($body = null)
@@ -601,8 +647,9 @@ public function fakeOuterNumberSerialize($body = null)
      *
      * @param  \Swagger\Client\Model\OuterNumber $body Input number as post body (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\OuterNumber, HTTP status code, HTTP response headers (array of strings)
      */
     public function fakeOuterNumberSerializeWithHttpInfo($body = null)
@@ -614,13 +661,17 @@ public function fakeOuterNumberSerializeWithHttpInfo($body = null)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -677,6 +728,7 @@ public function fakeOuterNumberSerializeWithHttpInfo($body = null)
      * @param  \Swagger\Client\Model\OuterNumber $body Input number as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function fakeOuterNumberSerializeAsync($body = null)
@@ -697,6 +749,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\OuterNumber $body Input number as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function fakeOuterNumberSerializeAsyncWithHttpInfo($body = null)
@@ -725,17 +778,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -747,6 +806,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\OuterNumber $body Input number as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function fakeOuterNumberSerializeRequest($body = null)
@@ -782,9 +842,16 @@ protected function fakeOuterNumberSerializeRequest($body = null)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -799,7 +866,7 @@ protected function fakeOuterNumberSerializeRequest($body = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -833,8 +900,9 @@ protected function fakeOuterNumberSerializeRequest($body = null)
      *
      * @param  \Swagger\Client\Model\OuterString $body Input string as post body (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\OuterString
      */
     public function fakeOuterStringSerialize($body = null)
@@ -848,8 +916,9 @@ public function fakeOuterStringSerialize($body = null)
      *
      * @param  \Swagger\Client\Model\OuterString $body Input string as post body (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\OuterString, HTTP status code, HTTP response headers (array of strings)
      */
     public function fakeOuterStringSerializeWithHttpInfo($body = null)
@@ -861,13 +930,17 @@ public function fakeOuterStringSerializeWithHttpInfo($body = null)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -924,6 +997,7 @@ public function fakeOuterStringSerializeWithHttpInfo($body = null)
      * @param  \Swagger\Client\Model\OuterString $body Input string as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function fakeOuterStringSerializeAsync($body = null)
@@ -944,6 +1018,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\OuterString $body Input string as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function fakeOuterStringSerializeAsyncWithHttpInfo($body = null)
@@ -972,17 +1047,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -994,6 +1075,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\OuterString $body Input string as post body (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function fakeOuterStringSerializeRequest($body = null)
@@ -1029,9 +1111,16 @@ protected function fakeOuterStringSerializeRequest($body = null)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -1046,7 +1135,7 @@ protected function fakeOuterStringSerializeRequest($body = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1081,8 +1170,9 @@ protected function fakeOuterStringSerializeRequest($body = null)
      * @param  \Swagger\Client\Model\User $body body (required)
      * @param  string $query query (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function testBodyWithQueryParams($body, $query)
@@ -1096,8 +1186,9 @@ public function testBodyWithQueryParams($body, $query)
      * @param  \Swagger\Client\Model\User $body (required)
      * @param  string $query (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function testBodyWithQueryParamsWithHttpInfo($body, $query)
@@ -1109,13 +1200,17 @@ public function testBodyWithQueryParamsWithHttpInfo($body, $query)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1151,6 +1246,7 @@ public function testBodyWithQueryParamsWithHttpInfo($body, $query)
      * @param  string $query (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testBodyWithQueryParamsAsync($body, $query)
@@ -1172,6 +1268,7 @@ function ($response) {
      * @param  string $query (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testBodyWithQueryParamsAsyncWithHttpInfo($body, $query)
@@ -1186,17 +1283,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1209,6 +1312,7 @@ function ($exception) {
      * @param  string $query (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function testBodyWithQueryParamsRequest($body, $query)
@@ -1260,9 +1364,16 @@ protected function testBodyWithQueryParamsRequest($body, $query)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -1277,7 +1388,7 @@ protected function testBodyWithQueryParamsRequest($body, $query)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1313,8 +1424,9 @@ protected function testBodyWithQueryParamsRequest($body, $query)
      *
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\Client
      */
     public function testClientModel($body)
@@ -1330,8 +1442,9 @@ public function testClientModel($body)
      *
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\Client, HTTP status code, HTTP response headers (array of strings)
      */
     public function testClientModelWithHttpInfo($body)
@@ -1343,13 +1456,17 @@ public function testClientModelWithHttpInfo($body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1406,6 +1523,7 @@ public function testClientModelWithHttpInfo($body)
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testClientModelAsync($body)
@@ -1426,6 +1544,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testClientModelAsyncWithHttpInfo($body)
@@ -1454,17 +1573,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1476,6 +1601,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function testClientModelRequest($body)
@@ -1517,9 +1643,16 @@ protected function testClientModelRequest($body)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -1534,7 +1667,7 @@ protected function testClientModelRequest($body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1583,8 +1716,9 @@ protected function testClientModelRequest($body)
      * @param  string $password None (optional)
      * @param  string $callback None (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function testEndpointParameters($number, $double, $pattern_without_delimiter, $byte, $integer = null, $int32 = null, $int64 = null, $float = null, $string = null, $binary = null, $date = null, $date_time = null, $password = null, $callback = null)
@@ -1612,8 +1746,9 @@ public function testEndpointParameters($number, $double, $pattern_without_delimi
      * @param  string $password None (optional)
      * @param  string $callback None (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function testEndpointParametersWithHttpInfo($number, $double, $pattern_without_delimiter, $byte, $integer = null, $int32 = null, $int64 = null, $float = null, $string = null, $binary = null, $date = null, $date_time = null, $password = null, $callback = null)
@@ -1625,13 +1760,17 @@ public function testEndpointParametersWithHttpInfo($number, $double, $pattern_wi
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1679,6 +1818,7 @@ public function testEndpointParametersWithHttpInfo($number, $double, $pattern_wi
      * @param  string $callback None (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testEndpointParametersAsync($number, $double, $pattern_without_delimiter, $byte, $integer = null, $int32 = null, $int64 = null, $float = null, $string = null, $binary = null, $date = null, $date_time = null, $password = null, $callback = null)
@@ -1712,6 +1852,7 @@ function ($response) {
      * @param  string $callback None (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testEndpointParametersAsyncWithHttpInfo($number, $double, $pattern_without_delimiter, $byte, $integer = null, $int32 = null, $int64 = null, $float = null, $string = null, $binary = null, $date = null, $date_time = null, $password = null, $callback = null)
@@ -1726,17 +1867,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1761,6 +1908,7 @@ function ($exception) {
      * @param  string $callback None (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function testEndpointParametersRequest($number, $double, $pattern_without_delimiter, $byte, $integer = null, $int32 = null, $int64 = null, $float = null, $string = null, $binary = null, $date = null, $date_time = null, $password = null, $callback = null)
@@ -1920,9 +2068,16 @@ protected function testEndpointParametersRequest($number, $double, $pattern_with
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -1937,7 +2092,7 @@ protected function testEndpointParametersRequest($number, $double, $pattern_with
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1984,8 +2139,9 @@ protected function testEndpointParametersRequest($number, $double, $pattern_with
      * @param  int $enum_query_integer Query parameter enum test (double) (optional)
      * @param  double $enum_query_double Query parameter enum test (double) (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function testEnumParameters($enum_form_string_array = null, $enum_form_string = '-efg', $enum_header_string_array = null, $enum_header_string = '-efg', $enum_query_string_array = null, $enum_query_string = '-efg', $enum_query_integer = null, $enum_query_double = null)
@@ -2007,8 +2163,9 @@ public function testEnumParameters($enum_form_string_array = null, $enum_form_st
      * @param  int $enum_query_integer Query parameter enum test (double) (optional)
      * @param  double $enum_query_double Query parameter enum test (double) (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function testEnumParametersWithHttpInfo($enum_form_string_array = null, $enum_form_string = '-efg', $enum_header_string_array = null, $enum_header_string = '-efg', $enum_query_string_array = null, $enum_query_string = '-efg', $enum_query_integer = null, $enum_query_double = null)
@@ -2020,13 +2177,17 @@ public function testEnumParametersWithHttpInfo($enum_form_string_array = null, $
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -2068,6 +2229,7 @@ public function testEnumParametersWithHttpInfo($enum_form_string_array = null, $
      * @param  double $enum_query_double Query parameter enum test (double) (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testEnumParametersAsync($enum_form_string_array = null, $enum_form_string = '-efg', $enum_header_string_array = null, $enum_header_string = '-efg', $enum_query_string_array = null, $enum_query_string = '-efg', $enum_query_integer = null, $enum_query_double = null)
@@ -2095,6 +2257,7 @@ function ($response) {
      * @param  double $enum_query_double Query parameter enum test (double) (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testEnumParametersAsyncWithHttpInfo($enum_form_string_array = null, $enum_form_string = '-efg', $enum_header_string_array = null, $enum_header_string = '-efg', $enum_query_string_array = null, $enum_query_string = '-efg', $enum_query_integer = null, $enum_query_double = null)
@@ -2109,17 +2272,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -2138,6 +2307,7 @@ function ($exception) {
      * @param  double $enum_query_double Query parameter enum test (double) (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function testEnumParametersRequest($enum_form_string_array = null, $enum_form_string = '-efg', $enum_header_string_array = null, $enum_header_string = '-efg', $enum_query_string_array = null, $enum_query_string = '-efg', $enum_query_integer = null, $enum_query_double = null)
@@ -2152,8 +2322,8 @@ protected function testEnumParametersRequest($enum_form_string_array = null, $en
 
         // query params
         if (is_array($enum_query_string_array)) {
-            $enum_query_string_array = ObjectSerializer::serializeCollection($enum_query_string_array, 'csv', true);
-        }
+            $queryParams['enum_query_string_array'] = $enum_query_string_array;
+        } else
         if ($enum_query_string_array !== null) {
             $queryParams['enum_query_string_array'] = ObjectSerializer::toQueryValue($enum_query_string_array);
         }
@@ -2208,9 +2378,16 @@ protected function testEnumParametersRequest($enum_form_string_array = null, $en
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -2225,7 +2402,7 @@ protected function testEnumParametersRequest($enum_form_string_array = null, $en
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -2261,8 +2438,9 @@ protected function testEnumParametersRequest($enum_form_string_array = null, $en
      *
      * @param  object $param request body (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function testInlineAdditionalProperties($param)
@@ -2277,8 +2455,9 @@ public function testInlineAdditionalProperties($param)
      *
      * @param  object $param request body (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function testInlineAdditionalPropertiesWithHttpInfo($param)
@@ -2290,13 +2469,17 @@ public function testInlineAdditionalPropertiesWithHttpInfo($param)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -2331,6 +2514,7 @@ public function testInlineAdditionalPropertiesWithHttpInfo($param)
      * @param  object $param request body (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testInlineAdditionalPropertiesAsync($param)
@@ -2351,6 +2535,7 @@ function ($response) {
      * @param  object $param request body (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testInlineAdditionalPropertiesAsyncWithHttpInfo($param)
@@ -2365,17 +2550,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -2387,6 +2578,7 @@ function ($exception) {
      * @param  object $param request body (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function testInlineAdditionalPropertiesRequest($param)
@@ -2428,9 +2620,16 @@ protected function testInlineAdditionalPropertiesRequest($param)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -2445,7 +2644,7 @@ protected function testInlineAdditionalPropertiesRequest($param)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -2482,8 +2681,9 @@ protected function testInlineAdditionalPropertiesRequest($param)
      * @param  string $param field1 (required)
      * @param  string $param2 field2 (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function testJsonFormData($param, $param2)
@@ -2499,8 +2699,9 @@ public function testJsonFormData($param, $param2)
      * @param  string $param field1 (required)
      * @param  string $param2 field2 (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function testJsonFormDataWithHttpInfo($param, $param2)
@@ -2512,13 +2713,17 @@ public function testJsonFormDataWithHttpInfo($param, $param2)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -2554,6 +2759,7 @@ public function testJsonFormDataWithHttpInfo($param, $param2)
      * @param  string $param2 field2 (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testJsonFormDataAsync($param, $param2)
@@ -2575,6 +2781,7 @@ function ($response) {
      * @param  string $param2 field2 (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testJsonFormDataAsyncWithHttpInfo($param, $param2)
@@ -2589,17 +2796,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -2612,6 +2825,7 @@ function ($exception) {
      * @param  string $param2 field2 (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function testJsonFormDataRequest($param, $param2)
@@ -2664,9 +2878,16 @@ protected function testJsonFormDataRequest($param, $param2)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -2681,7 +2902,7 @@ protected function testJsonFormDataRequest($param, $param2)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeClassnameTags123Api.php b/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeClassnameTags123Api.php
index 2b9ce933a6f..c5806b89ab7 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeClassnameTags123Api.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Api/FakeClassnameTags123Api.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -30,7 +30,8 @@
 
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
+use GuzzleHttp\Exception\ResponseException;
+use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\Psr7\MultipartStream;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\RequestOptions;
@@ -70,9 +71,9 @@ class FakeClassnameTags123Api
      * @param HeaderSelector  $selector
      */
     public function __construct(
-        ClientInterface $client = null,
-        Configuration $config = null,
-        HeaderSelector $selector = null
+        ?ClientInterface $client = null,
+        ?Configuration $config = null,
+        ?HeaderSelector $selector = null
     ) {
         $this->client = $client ?: new Client();
         $this->config = $config ?: new Configuration();
@@ -94,8 +95,9 @@ public function getConfig()
      *
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\Client
      */
     public function testClassname($body)
@@ -111,8 +113,9 @@ public function testClassname($body)
      *
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\Client, HTTP status code, HTTP response headers (array of strings)
      */
     public function testClassnameWithHttpInfo($body)
@@ -124,13 +127,17 @@ public function testClassnameWithHttpInfo($body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -187,6 +194,7 @@ public function testClassnameWithHttpInfo($body)
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testClassnameAsync($body)
@@ -207,6 +215,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function testClassnameAsyncWithHttpInfo($body)
@@ -235,17 +244,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -257,6 +272,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\Client $body client model (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function testClassnameRequest($body)
@@ -298,9 +314,16 @@ protected function testClassnameRequest($body)
         if (isset($_tempBody)) {
             // $_tempBody is the method argument, if present
             $httpBody = $_tempBody;
-            // \stdClass has no __toString(), so we should encode it manually
-            if ($httpBody instanceof \stdClass && $headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($httpBody);
+            
+            if($headers['Content-Type'] === 'application/json') {
+                // \stdClass has no __toString(), so we should encode it manually
+                if ($httpBody instanceof \stdClass) {
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
+                }
+                // array has no __toString(), so we should encode it manually
+                if(is_array($httpBody)) {
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
+                }
             }
         } elseif (count($formParams) > 0) {
             if ($multipart) {
@@ -315,7 +338,7 @@ protected function testClassnameRequest($body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Api/PetApi.php b/samples/client/petstore/php/SwaggerClient-php/lib/Api/PetApi.php
index 85df4c18fa1..6429759b566 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Api/PetApi.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Api/PetApi.php
@@ -12,12 +12,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -30,7 +30,8 @@
 
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
+use GuzzleHttp\Exception\ResponseException;
+use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\Psr7\MultipartStream;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\RequestOptions;
@@ -70,9 +71,9 @@ class PetApi
      * @param HeaderSelector  $selector
      */
     public function __construct(
-        ClientInterface $client = null,
-        Configuration $config = null,
-        HeaderSelector $selector = null
+        ?ClientInterface $client = null,
+        ?Configuration $config = null,
+        ?HeaderSelector $selector = null
     ) {
         $this->client = $client ?: new Client();
         $this->config = $config ?: new Configuration();
@@ -94,8 +95,9 @@ public function getConfig()
      *
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function addPet($body)
@@ -110,8 +112,9 @@ public function addPet($body)
      *
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function addPetWithHttpInfo($body)
@@ -123,13 +126,17 @@ public function addPetWithHttpInfo($body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -164,6 +171,7 @@ public function addPetWithHttpInfo($body)
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function addPetAsync($body)
@@ -184,6 +192,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function addPetAsyncWithHttpInfo($body)
@@ -198,17 +207,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -220,6 +235,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function addPetRequest($body)
@@ -265,11 +281,11 @@ protected function addPetRequest($body)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -285,7 +301,7 @@ protected function addPetRequest($body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -326,8 +342,9 @@ protected function addPetRequest($body)
      * @param  int $pet_id Pet id to delete (required)
      * @param  string $api_key api_key (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function deletePet($pet_id, $api_key = null)
@@ -343,8 +360,9 @@ public function deletePet($pet_id, $api_key = null)
      * @param  int $pet_id Pet id to delete (required)
      * @param  string $api_key (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function deletePetWithHttpInfo($pet_id, $api_key = null)
@@ -356,13 +374,17 @@ public function deletePetWithHttpInfo($pet_id, $api_key = null)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -398,6 +420,7 @@ public function deletePetWithHttpInfo($pet_id, $api_key = null)
      * @param  string $api_key (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function deletePetAsync($pet_id, $api_key = null)
@@ -419,6 +442,7 @@ function ($response) {
      * @param  string $api_key (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function deletePetAsyncWithHttpInfo($pet_id, $api_key = null)
@@ -433,17 +457,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -456,6 +486,7 @@ function ($exception) {
      * @param  string $api_key (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function deletePetRequest($pet_id, $api_key = null)
@@ -510,11 +541,11 @@ protected function deletePetRequest($pet_id, $api_key = null)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -530,7 +561,7 @@ protected function deletePetRequest($pet_id, $api_key = null)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -570,8 +601,9 @@ protected function deletePetRequest($pet_id, $api_key = null)
      *
      * @param  string[] $status Status values that need to be considered for filter (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\Pet[]
      */
     public function findPetsByStatus($status)
@@ -587,8 +619,9 @@ public function findPetsByStatus($status)
      *
      * @param  string[] $status Status values that need to be considered for filter (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\Pet[], HTTP status code, HTTP response headers (array of strings)
      */
     public function findPetsByStatusWithHttpInfo($status)
@@ -600,13 +633,17 @@ public function findPetsByStatusWithHttpInfo($status)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -663,6 +700,7 @@ public function findPetsByStatusWithHttpInfo($status)
      * @param  string[] $status Status values that need to be considered for filter (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function findPetsByStatusAsync($status)
@@ -683,6 +721,7 @@ function ($response) {
      * @param  string[] $status Status values that need to be considered for filter (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function findPetsByStatusAsyncWithHttpInfo($status)
@@ -711,17 +750,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -733,6 +778,7 @@ function ($exception) {
      * @param  string[] $status Status values that need to be considered for filter (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function findPetsByStatusRequest($status)
@@ -782,11 +828,11 @@ protected function findPetsByStatusRequest($status)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -802,7 +848,7 @@ protected function findPetsByStatusRequest($status)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -842,8 +888,9 @@ protected function findPetsByStatusRequest($status)
      *
      * @param  string[] $tags Tags to filter by (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\Pet[]
      */
     public function findPetsByTags($tags)
@@ -859,8 +906,9 @@ public function findPetsByTags($tags)
      *
      * @param  string[] $tags Tags to filter by (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\Pet[], HTTP status code, HTTP response headers (array of strings)
      */
     public function findPetsByTagsWithHttpInfo($tags)
@@ -872,13 +920,17 @@ public function findPetsByTagsWithHttpInfo($tags)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -935,6 +987,7 @@ public function findPetsByTagsWithHttpInfo($tags)
      * @param  string[] $tags Tags to filter by (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function findPetsByTagsAsync($tags)
@@ -955,6 +1008,7 @@ function ($response) {
      * @param  string[] $tags Tags to filter by (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function findPetsByTagsAsyncWithHttpInfo($tags)
@@ -983,17 +1037,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1005,6 +1065,7 @@ function ($exception) {
      * @param  string[] $tags Tags to filter by (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function findPetsByTagsRequest($tags)
@@ -1054,11 +1115,11 @@ protected function findPetsByTagsRequest($tags)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -1074,7 +1135,7 @@ protected function findPetsByTagsRequest($tags)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1114,8 +1175,9 @@ protected function findPetsByTagsRequest($tags)
      *
      * @param  int $pet_id ID of pet to return (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\Pet
      */
     public function getPetById($pet_id)
@@ -1131,8 +1193,9 @@ public function getPetById($pet_id)
      *
      * @param  int $pet_id ID of pet to return (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\Pet, HTTP status code, HTTP response headers (array of strings)
      */
     public function getPetByIdWithHttpInfo($pet_id)
@@ -1144,13 +1207,17 @@ public function getPetByIdWithHttpInfo($pet_id)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1207,6 +1274,7 @@ public function getPetByIdWithHttpInfo($pet_id)
      * @param  int $pet_id ID of pet to return (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function getPetByIdAsync($pet_id)
@@ -1227,6 +1295,7 @@ function ($response) {
      * @param  int $pet_id ID of pet to return (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function getPetByIdAsyncWithHttpInfo($pet_id)
@@ -1255,17 +1324,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1277,6 +1352,7 @@ function ($exception) {
      * @param  int $pet_id ID of pet to return (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function getPetByIdRequest($pet_id)
@@ -1327,11 +1403,11 @@ protected function getPetByIdRequest($pet_id)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -1347,7 +1423,7 @@ protected function getPetByIdRequest($pet_id)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1388,8 +1464,9 @@ protected function getPetByIdRequest($pet_id)
      *
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function updatePet($body)
@@ -1404,8 +1481,9 @@ public function updatePet($body)
      *
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function updatePetWithHttpInfo($body)
@@ -1417,13 +1495,17 @@ public function updatePetWithHttpInfo($body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1458,6 +1540,7 @@ public function updatePetWithHttpInfo($body)
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function updatePetAsync($body)
@@ -1478,6 +1561,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function updatePetAsyncWithHttpInfo($body)
@@ -1492,17 +1576,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1514,6 +1604,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\Pet $body Pet object that needs to be added to the store (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function updatePetRequest($body)
@@ -1559,11 +1650,11 @@ protected function updatePetRequest($body)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -1579,7 +1670,7 @@ protected function updatePetRequest($body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1621,8 +1712,9 @@ protected function updatePetRequest($body)
      * @param  string $name Updated name of the pet (optional)
      * @param  string $status Updated status of the pet (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function updatePetWithForm($pet_id, $name = null, $status = null)
@@ -1639,8 +1731,9 @@ public function updatePetWithForm($pet_id, $name = null, $status = null)
      * @param  string $name Updated name of the pet (optional)
      * @param  string $status Updated status of the pet (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function updatePetWithFormWithHttpInfo($pet_id, $name = null, $status = null)
@@ -1652,13 +1745,17 @@ public function updatePetWithFormWithHttpInfo($pet_id, $name = null, $status = n
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1695,6 +1792,7 @@ public function updatePetWithFormWithHttpInfo($pet_id, $name = null, $status = n
      * @param  string $status Updated status of the pet (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function updatePetWithFormAsync($pet_id, $name = null, $status = null)
@@ -1717,6 +1815,7 @@ function ($response) {
      * @param  string $status Updated status of the pet (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function updatePetWithFormAsyncWithHttpInfo($pet_id, $name = null, $status = null)
@@ -1731,17 +1830,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1755,6 +1860,7 @@ function ($exception) {
      * @param  string $status Updated status of the pet (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function updatePetWithFormRequest($pet_id, $name = null, $status = null)
@@ -1813,11 +1919,11 @@ protected function updatePetWithFormRequest($pet_id, $name = null, $status = nul
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -1833,7 +1939,7 @@ protected function updatePetWithFormRequest($pet_id, $name = null, $status = nul
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1875,8 +1981,9 @@ protected function updatePetWithFormRequest($pet_id, $name = null, $status = nul
      * @param  string $additional_metadata Additional data to pass to server (optional)
      * @param  \SplFileObject $file file to upload (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\ApiResponse
      */
     public function uploadFile($pet_id, $additional_metadata = null, $file = null)
@@ -1894,8 +2001,9 @@ public function uploadFile($pet_id, $additional_metadata = null, $file = null)
      * @param  string $additional_metadata Additional data to pass to server (optional)
      * @param  \SplFileObject $file file to upload (optional)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\ApiResponse, HTTP status code, HTTP response headers (array of strings)
      */
     public function uploadFileWithHttpInfo($pet_id, $additional_metadata = null, $file = null)
@@ -1907,13 +2015,17 @@ public function uploadFileWithHttpInfo($pet_id, $additional_metadata = null, $fi
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1972,6 +2084,7 @@ public function uploadFileWithHttpInfo($pet_id, $additional_metadata = null, $fi
      * @param  \SplFileObject $file file to upload (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function uploadFileAsync($pet_id, $additional_metadata = null, $file = null)
@@ -1994,6 +2107,7 @@ function ($response) {
      * @param  \SplFileObject $file file to upload (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function uploadFileAsyncWithHttpInfo($pet_id, $additional_metadata = null, $file = null)
@@ -2022,17 +2136,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -2046,6 +2166,7 @@ function ($exception) {
      * @param  \SplFileObject $file file to upload (optional)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function uploadFileRequest($pet_id, $additional_metadata = null, $file = null)
@@ -2081,7 +2202,7 @@ protected function uploadFileRequest($pet_id, $additional_metadata = null, $file
         // form params
         if ($file !== null) {
             $multipart = true;
-            $formParams['file'] = \GuzzleHttp\Psr7\try_fopen(ObjectSerializer::toFormValue($file), 'rb');
+            $formParams['file'] = \GuzzleHttp\Psr7\Utils::tryFopen(ObjectSerializer::toFormValue($file), 'rb');
         }
         // body params
         $_tempBody = null;
@@ -2105,11 +2226,11 @@ protected function uploadFileRequest($pet_id, $additional_metadata = null, $file
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -2125,7 +2246,7 @@ protected function uploadFileRequest($pet_id, $additional_metadata = null, $file
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Api/StoreApi.php b/samples/client/petstore/php/SwaggerClient-php/lib/Api/StoreApi.php
index a65dd45a52c..91b30a9ec43 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Api/StoreApi.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Api/StoreApi.php
@@ -12,12 +12,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -30,7 +30,8 @@
 
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
+use GuzzleHttp\Exception\ResponseException;
+use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\Psr7\MultipartStream;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\RequestOptions;
@@ -70,9 +71,9 @@ class StoreApi
      * @param HeaderSelector  $selector
      */
     public function __construct(
-        ClientInterface $client = null,
-        Configuration $config = null,
-        HeaderSelector $selector = null
+        ?ClientInterface $client = null,
+        ?Configuration $config = null,
+        ?HeaderSelector $selector = null
     ) {
         $this->client = $client ?: new Client();
         $this->config = $config ?: new Configuration();
@@ -94,8 +95,9 @@ public function getConfig()
      *
      * @param  string $order_id ID of the order that needs to be deleted (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function deleteOrder($order_id)
@@ -110,8 +112,9 @@ public function deleteOrder($order_id)
      *
      * @param  string $order_id ID of the order that needs to be deleted (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function deleteOrderWithHttpInfo($order_id)
@@ -123,13 +126,17 @@ public function deleteOrderWithHttpInfo($order_id)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -164,6 +171,7 @@ public function deleteOrderWithHttpInfo($order_id)
      * @param  string $order_id ID of the order that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function deleteOrderAsync($order_id)
@@ -184,6 +192,7 @@ function ($response) {
      * @param  string $order_id ID of the order that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function deleteOrderAsyncWithHttpInfo($order_id)
@@ -198,17 +207,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -220,6 +235,7 @@ function ($exception) {
      * @param  string $order_id ID of the order that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function deleteOrderRequest($order_id)
@@ -231,7 +247,7 @@ protected function deleteOrderRequest($order_id)
             );
         }
 
-        $resourcePath = '/store/order/{orderId}';
+        $resourcePath = '/store/order/{order_id}';
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
@@ -242,7 +258,7 @@ protected function deleteOrderRequest($order_id)
         // path params
         if ($order_id !== null) {
             $resourcePath = str_replace(
-                '{' . 'orderId' . '}',
+                '{' . 'order_id' . '}',
                 ObjectSerializer::toPathValue($order_id),
                 $resourcePath
             );
@@ -270,11 +286,11 @@ protected function deleteOrderRequest($order_id)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -290,7 +306,7 @@ protected function deleteOrderRequest($order_id)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -325,8 +341,9 @@ protected function deleteOrderRequest($order_id)
      * Returns pet inventories by status
      *
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return map[string,int]
      */
     public function getInventory()
@@ -341,8 +358,9 @@ public function getInventory()
      * Returns pet inventories by status
      *
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of map[string,int], HTTP status code, HTTP response headers (array of strings)
      */
     public function getInventoryWithHttpInfo()
@@ -354,13 +372,17 @@ public function getInventoryWithHttpInfo()
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -416,6 +438,7 @@ public function getInventoryWithHttpInfo()
      *
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function getInventoryAsync()
@@ -435,6 +458,7 @@ function ($response) {
      *
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function getInventoryAsyncWithHttpInfo()
@@ -463,17 +487,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -484,6 +514,7 @@ function ($exception) {
      *
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function getInventoryRequest()
@@ -520,11 +551,11 @@ protected function getInventoryRequest()
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -540,7 +571,7 @@ protected function getInventoryRequest()
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -581,8 +612,9 @@ protected function getInventoryRequest()
      *
      * @param  int $order_id ID of pet that needs to be fetched (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\Order
      */
     public function getOrderById($order_id)
@@ -598,8 +630,9 @@ public function getOrderById($order_id)
      *
      * @param  int $order_id ID of pet that needs to be fetched (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\Order, HTTP status code, HTTP response headers (array of strings)
      */
     public function getOrderByIdWithHttpInfo($order_id)
@@ -611,13 +644,17 @@ public function getOrderByIdWithHttpInfo($order_id)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -674,6 +711,7 @@ public function getOrderByIdWithHttpInfo($order_id)
      * @param  int $order_id ID of pet that needs to be fetched (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function getOrderByIdAsync($order_id)
@@ -694,6 +732,7 @@ function ($response) {
      * @param  int $order_id ID of pet that needs to be fetched (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function getOrderByIdAsyncWithHttpInfo($order_id)
@@ -722,17 +761,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -744,6 +789,7 @@ function ($exception) {
      * @param  int $order_id ID of pet that needs to be fetched (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function getOrderByIdRequest($order_id)
@@ -762,7 +808,7 @@ protected function getOrderByIdRequest($order_id)
         }
 
 
-        $resourcePath = '/store/order/{orderId}';
+        $resourcePath = '/store/order/{order_id}';
         $formParams = [];
         $queryParams = [];
         $headerParams = [];
@@ -773,7 +819,7 @@ protected function getOrderByIdRequest($order_id)
         // path params
         if ($order_id !== null) {
             $resourcePath = str_replace(
-                '{' . 'orderId' . '}',
+                '{' . 'order_id' . '}',
                 ObjectSerializer::toPathValue($order_id),
                 $resourcePath
             );
@@ -801,11 +847,11 @@ protected function getOrderByIdRequest($order_id)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -821,7 +867,7 @@ protected function getOrderByIdRequest($order_id)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -857,8 +903,9 @@ protected function getOrderByIdRequest($order_id)
      *
      * @param  \Swagger\Client\Model\Order $body order placed for purchasing the pet (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\Order
      */
     public function placeOrder($body)
@@ -874,8 +921,9 @@ public function placeOrder($body)
      *
      * @param  \Swagger\Client\Model\Order $body order placed for purchasing the pet (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\Order, HTTP status code, HTTP response headers (array of strings)
      */
     public function placeOrderWithHttpInfo($body)
@@ -887,13 +935,17 @@ public function placeOrderWithHttpInfo($body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -950,6 +1002,7 @@ public function placeOrderWithHttpInfo($body)
      * @param  \Swagger\Client\Model\Order $body order placed for purchasing the pet (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function placeOrderAsync($body)
@@ -970,6 +1023,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\Order $body order placed for purchasing the pet (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function placeOrderAsyncWithHttpInfo($body)
@@ -998,17 +1052,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1020,6 +1080,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\Order $body order placed for purchasing the pet (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function placeOrderRequest($body)
@@ -1065,11 +1126,11 @@ protected function placeOrderRequest($body)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -1085,7 +1146,7 @@ protected function placeOrderRequest($body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Api/UserApi.php b/samples/client/petstore/php/SwaggerClient-php/lib/Api/UserApi.php
index edf55946bae..6d8ce3a1bd7 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Api/UserApi.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Api/UserApi.php
@@ -12,12 +12,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -30,7 +30,8 @@
 
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
-use GuzzleHttp\Exception\RequestException;
+use GuzzleHttp\Exception\ResponseException;
+use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\Psr7\MultipartStream;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\RequestOptions;
@@ -70,9 +71,9 @@ class UserApi
      * @param HeaderSelector  $selector
      */
     public function __construct(
-        ClientInterface $client = null,
-        Configuration $config = null,
-        HeaderSelector $selector = null
+        ?ClientInterface $client = null,
+        ?Configuration $config = null,
+        ?HeaderSelector $selector = null
     ) {
         $this->client = $client ?: new Client();
         $this->config = $config ?: new Configuration();
@@ -94,8 +95,9 @@ public function getConfig()
      *
      * @param  \Swagger\Client\Model\User $body Created user object (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function createUser($body)
@@ -110,8 +112,9 @@ public function createUser($body)
      *
      * @param  \Swagger\Client\Model\User $body Created user object (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function createUserWithHttpInfo($body)
@@ -123,13 +126,17 @@ public function createUserWithHttpInfo($body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -164,6 +171,7 @@ public function createUserWithHttpInfo($body)
      * @param  \Swagger\Client\Model\User $body Created user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function createUserAsync($body)
@@ -184,6 +192,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\User $body Created user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function createUserAsyncWithHttpInfo($body)
@@ -198,17 +207,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -220,6 +235,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\User $body Created user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function createUserRequest($body)
@@ -265,11 +281,11 @@ protected function createUserRequest($body)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -285,7 +301,7 @@ protected function createUserRequest($body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -321,8 +337,9 @@ protected function createUserRequest($body)
      *
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function createUsersWithArrayInput($body)
@@ -337,8 +354,9 @@ public function createUsersWithArrayInput($body)
      *
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function createUsersWithArrayInputWithHttpInfo($body)
@@ -350,13 +368,17 @@ public function createUsersWithArrayInputWithHttpInfo($body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -391,6 +413,7 @@ public function createUsersWithArrayInputWithHttpInfo($body)
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function createUsersWithArrayInputAsync($body)
@@ -411,6 +434,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function createUsersWithArrayInputAsyncWithHttpInfo($body)
@@ -425,17 +449,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -447,6 +477,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function createUsersWithArrayInputRequest($body)
@@ -492,11 +523,11 @@ protected function createUsersWithArrayInputRequest($body)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -512,7 +543,7 @@ protected function createUsersWithArrayInputRequest($body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -548,8 +579,9 @@ protected function createUsersWithArrayInputRequest($body)
      *
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function createUsersWithListInput($body)
@@ -564,8 +596,9 @@ public function createUsersWithListInput($body)
      *
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function createUsersWithListInputWithHttpInfo($body)
@@ -577,13 +610,17 @@ public function createUsersWithListInputWithHttpInfo($body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -618,6 +655,7 @@ public function createUsersWithListInputWithHttpInfo($body)
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function createUsersWithListInputAsync($body)
@@ -638,6 +676,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function createUsersWithListInputAsyncWithHttpInfo($body)
@@ -652,17 +691,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -674,6 +719,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\User[] $body List of user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function createUsersWithListInputRequest($body)
@@ -719,11 +765,11 @@ protected function createUsersWithListInputRequest($body)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -739,7 +785,7 @@ protected function createUsersWithListInputRequest($body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -775,8 +821,9 @@ protected function createUsersWithListInputRequest($body)
      *
      * @param  string $username The name that needs to be deleted (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function deleteUser($username)
@@ -791,8 +838,9 @@ public function deleteUser($username)
      *
      * @param  string $username The name that needs to be deleted (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function deleteUserWithHttpInfo($username)
@@ -804,13 +852,17 @@ public function deleteUserWithHttpInfo($username)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -845,6 +897,7 @@ public function deleteUserWithHttpInfo($username)
      * @param  string $username The name that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function deleteUserAsync($username)
@@ -865,6 +918,7 @@ function ($response) {
      * @param  string $username The name that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function deleteUserAsyncWithHttpInfo($username)
@@ -879,17 +933,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -901,6 +961,7 @@ function ($exception) {
      * @param  string $username The name that needs to be deleted (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function deleteUserRequest($username)
@@ -951,11 +1012,11 @@ protected function deleteUserRequest($username)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -971,7 +1032,7 @@ protected function deleteUserRequest($username)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1007,8 +1068,9 @@ protected function deleteUserRequest($username)
      *
      * @param  string $username The name that needs to be fetched. Use user1 for testing. (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \Swagger\Client\Model\User
      */
     public function getUserByName($username)
@@ -1024,8 +1086,9 @@ public function getUserByName($username)
      *
      * @param  string $username The name that needs to be fetched. Use user1 for testing. (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of \Swagger\Client\Model\User, HTTP status code, HTTP response headers (array of strings)
      */
     public function getUserByNameWithHttpInfo($username)
@@ -1037,13 +1100,17 @@ public function getUserByNameWithHttpInfo($username)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1100,6 +1167,7 @@ public function getUserByNameWithHttpInfo($username)
      * @param  string $username The name that needs to be fetched. Use user1 for testing. (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function getUserByNameAsync($username)
@@ -1120,6 +1188,7 @@ function ($response) {
      * @param  string $username The name that needs to be fetched. Use user1 for testing. (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function getUserByNameAsyncWithHttpInfo($username)
@@ -1148,17 +1217,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1170,6 +1245,7 @@ function ($exception) {
      * @param  string $username The name that needs to be fetched. Use user1 for testing. (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function getUserByNameRequest($username)
@@ -1220,11 +1296,11 @@ protected function getUserByNameRequest($username)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -1240,7 +1316,7 @@ protected function getUserByNameRequest($username)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1277,8 +1353,9 @@ protected function getUserByNameRequest($username)
      * @param  string $username The user name for login (required)
      * @param  string $password The password for login in clear text (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return string
      */
     public function loginUser($username, $password)
@@ -1295,8 +1372,9 @@ public function loginUser($username, $password)
      * @param  string $username The user name for login (required)
      * @param  string $password The password for login in clear text (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of string, HTTP status code, HTTP response headers (array of strings)
      */
     public function loginUserWithHttpInfo($username, $password)
@@ -1308,13 +1386,17 @@ public function loginUserWithHttpInfo($username, $password)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1372,6 +1454,7 @@ public function loginUserWithHttpInfo($username, $password)
      * @param  string $password The password for login in clear text (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function loginUserAsync($username, $password)
@@ -1393,6 +1476,7 @@ function ($response) {
      * @param  string $password The password for login in clear text (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function loginUserAsyncWithHttpInfo($username, $password)
@@ -1421,17 +1505,23 @@ function ($response) use ($returnType) {
                     ];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1444,6 +1534,7 @@ function ($exception) {
      * @param  string $password The password for login in clear text (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function loginUserRequest($username, $password)
@@ -1500,11 +1591,11 @@ protected function loginUserRequest($username, $password)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -1520,7 +1611,7 @@ protected function loginUserRequest($username, $password)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1555,8 +1646,9 @@ protected function loginUserRequest($username, $password)
      * Logs out current logged in user session
      *
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function logoutUser()
@@ -1570,8 +1662,9 @@ public function logoutUser()
      * Logs out current logged in user session
      *
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function logoutUserWithHttpInfo()
@@ -1583,13 +1676,17 @@ public function logoutUserWithHttpInfo()
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1623,6 +1720,7 @@ public function logoutUserWithHttpInfo()
      *
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function logoutUserAsync()
@@ -1642,6 +1740,7 @@ function ($response) {
      *
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function logoutUserAsyncWithHttpInfo()
@@ -1656,17 +1755,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1677,6 +1782,7 @@ function ($exception) {
      *
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function logoutUserRequest()
@@ -1713,11 +1819,11 @@ protected function logoutUserRequest()
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -1733,7 +1839,7 @@ protected function logoutUserRequest()
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
@@ -1770,8 +1876,9 @@ protected function logoutUserRequest()
      * @param  string $username name that need to be deleted (required)
      * @param  \Swagger\Client\Model\User $body Updated user object (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return void
      */
     public function updateUser($username, $body)
@@ -1787,8 +1894,9 @@ public function updateUser($username, $body)
      * @param  string $username name that need to be deleted (required)
      * @param  \Swagger\Client\Model\User $body Updated user object (required)
      *
-     * @throws \Swagger\Client\ApiException on non-2xx response
+     * @throws \Swagger\Client\ApiException on non-2xx response or a failure without a response
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return array of null, HTTP status code, HTTP response headers (array of strings)
      */
     public function updateUserWithHttpInfo($username, $body)
@@ -1800,13 +1908,17 @@ public function updateUserWithHttpInfo($username, $body)
             $options = $this->createHttpClientOption();
             try {
                 $response = $this->client->send($request, $options);
-            } catch (RequestException $e) {
+            } catch (ResponseException $e) {
+                $response = $e->getResponse();
                 throw new ApiException(
                     "[{$e->getCode()}] {$e->getMessage()}",
                     $e->getCode(),
-                    $e->getResponse() ? $e->getResponse()->getHeaders() : null,
-                    $e->getResponse() ? $e->getResponse()->getBody()->getContents() : null
+                    $response->getHeaders(),
+                    $response->getBody()->getContents()
                 );
+            } catch (TransferException $e) {
+                // e.g. connection errors: there is no response
+                throw new ApiException("[{$e->getCode()}] {$e->getMessage()}", $e->getCode());
             }
 
             $statusCode = $response->getStatusCode();
@@ -1842,6 +1954,7 @@ public function updateUserWithHttpInfo($username, $body)
      * @param  \Swagger\Client\Model\User $body Updated user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function updateUserAsync($username, $body)
@@ -1863,6 +1976,7 @@ function ($response) {
      * @param  \Swagger\Client\Model\User $body Updated user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
     public function updateUserAsyncWithHttpInfo($username, $body)
@@ -1877,17 +1991,23 @@ function ($response) use ($returnType) {
                     return [null, $response->getStatusCode(), $response->getHeaders()];
                 },
                 function ($exception) {
-                    $response = $exception->getResponse();
-                    $statusCode = $response->getStatusCode();
-                    throw new ApiException(
-                        sprintf(
-                            '[%d] Error connecting to the API (%s)',
+                    if ($exception instanceof ResponseException) {
+                        $response = $exception->getResponse();
+                        $statusCode = $response->getStatusCode();
+                        throw new ApiException(
+                            sprintf(
+                                '[%d] Error connecting to the API (%s)',
+                                $statusCode,
+                                $exception->getRequest()->getUri()
+                            ),
                             $statusCode,
-                            $exception->getRequest()->getUri()
-                        ),
-                        $statusCode,
-                        $response->getHeaders(),
-                        $response->getBody()
+                            $response->getHeaders(),
+                            $response->getBody()
+                        );
+                    }
+                    throw new ApiException(
+                        sprintf('[%d] Error connecting to the API (%s)', $exception->getCode(), $exception->getMessage()),
+                        $exception->getCode()
                     );
                 }
             );
@@ -1900,6 +2020,7 @@ function ($exception) {
      * @param  \Swagger\Client\Model\User $body Updated user object (required)
      *
      * @throws \InvalidArgumentException
+     * @throws \JsonException
      * @return \GuzzleHttp\Psr7\Request
      */
     protected function updateUserRequest($username, $body)
@@ -1959,11 +2080,11 @@ protected function updateUserRequest($username, $body)
             if($headers['Content-Type'] === 'application/json') {
                 // \stdClass has no __toString(), so we should encode it manually
                 if ($httpBody instanceof \stdClass) {
-                    $httpBody = \GuzzleHttp\json_encode($httpBody);
+                    $httpBody = json_encode($httpBody, JSON_THROW_ON_ERROR);
                 }
                 // array has no __toString(), so we should encode it manually
                 if(is_array($httpBody)) {
-                    $httpBody = \GuzzleHttp\json_encode(ObjectSerializer::sanitizeForSerialization($httpBody));
+                    $httpBody = json_encode(ObjectSerializer::sanitizeForSerialization($httpBody), JSON_THROW_ON_ERROR);
                 }
             }
         } elseif (count($formParams) > 0) {
@@ -1979,7 +2100,7 @@ protected function updateUserRequest($username, $body)
                 $httpBody = new MultipartStream($multipartContents);
 
             } elseif ($headers['Content-Type'] === 'application/json') {
-                $httpBody = \GuzzleHttp\json_encode($formParams);
+                $httpBody = json_encode($formParams, JSON_THROW_ON_ERROR);
 
             } else {
                 // for HTTP post (form)
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/ApiException.php b/samples/client/petstore/php/SwaggerClient-php/lib/ApiException.php
index 38d93510c96..0815abef667 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/ApiException.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/ApiException.php
@@ -12,12 +12,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Configuration.php b/samples/client/petstore/php/SwaggerClient-php/lib/Configuration.php
index fb610939c5b..420e702d114 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Configuration.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Configuration.php
@@ -12,12 +12,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -81,7 +81,7 @@ class Configuration
      *
      * @var string
      */
-    protected $host = 'http://petstore.swagger.io/v2';
+    protected $host = 'http://petstore.swagger.io:80/v2';
 
     /**
      * User agent of the HTTP request, set to "PHP-Swagger" by default
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/HeaderSelector.php b/samples/client/petstore/php/SwaggerClient-php/lib/HeaderSelector.php
index 00235d1a77a..3d5b235048e 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/HeaderSelector.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/HeaderSelector.php
@@ -12,12 +12,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/AdditionalPropertiesClass.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/AdditionalPropertiesClass.php
index 74369007f91..4b28d446a78 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/AdditionalPropertiesClass.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/AdditionalPropertiesClass.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -264,6 +264,7 @@ public function setMapOfMapProperty($map_of_map_property)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -276,6 +277,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -289,6 +291,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -305,6 +308,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Animal.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Animal.php
index 706f7d82600..156732f0525 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Animal.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Animal.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -271,6 +271,7 @@ public function setColor($color)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -283,6 +284,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -296,6 +298,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -312,6 +315,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/AnimalFarm.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/AnimalFarm.php
index c0bffb19198..2bcc1788c19 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/AnimalFarm.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/AnimalFarm.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -209,6 +209,7 @@ public function valid()
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -221,6 +222,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -234,6 +236,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -250,6 +253,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ApiResponse.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ApiResponse.php
index e4439f756b1..c26a1598aa7 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ApiResponse.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ApiResponse.php
@@ -13,12 +13,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -36,7 +36,6 @@
  * ApiResponse Class Doc Comment
  *
  * @category Class
- * @description Describes the result of uploading an image resource
  * @package  Swagger\Client
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
@@ -295,6 +294,7 @@ public function setMessage($message)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -307,6 +307,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -320,6 +321,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -336,6 +338,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayOfArrayOfNumberOnly.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayOfArrayOfNumberOnly.php
index a9d2f531649..72009f51b6d 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayOfArrayOfNumberOnly.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayOfArrayOfNumberOnly.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -234,6 +234,7 @@ public function setArrayArrayNumber($array_array_number)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -246,6 +247,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -259,6 +261,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -275,6 +278,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayOfNumberOnly.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayOfNumberOnly.php
index c5b73d07dfc..0d88fdf0903 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayOfNumberOnly.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayOfNumberOnly.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -234,6 +234,7 @@ public function setArrayNumber($array_number)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -246,6 +247,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -259,6 +261,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -275,6 +278,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayTest.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayTest.php
index 9a7efa27283..74ee96b7a78 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ArrayTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -294,6 +294,7 @@ public function setArrayArrayOfModel($array_array_of_model)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -306,6 +307,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -319,6 +321,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -335,6 +338,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Boolean.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Boolean.php
new file mode 100644
index 00000000000..17ad7c90fbc
--- /dev/null
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Boolean.php
@@ -0,0 +1,63 @@
+<?php
+/**
+ * Boolean
+ *
+ * PHP version 5
+ *
+ * @category Class
+ * @package  Swagger\Client
+ * @author   Swagger Codegen team
+ * @link     https://github.com/swagger-api/swagger-codegen
+ */
+
+/**
+ * Swagger Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * OpenAPI spec version: 1.0.0
+ * Contact: apiteam@swagger.io
+ * Generated by: https://github.com/swagger-api/swagger-codegen.git
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
+ */
+
+/**
+ * NOTE: This class is auto generated by the swagger code generator program.
+ * https://github.com/swagger-api/swagger-codegen
+ * Do not edit the class manually.
+ */
+
+namespace Swagger\Client\Model;
+use \Swagger\Client\ObjectSerializer;
+
+/**
+ * Boolean Class Doc Comment
+ *
+ * @category Class
+ * @description True or False indicator
+ * @package  Swagger\Client
+ * @author   Swagger Codegen team
+ * @link     https://github.com/swagger-api/swagger-codegen
+ */
+class Boolean
+{
+    /**
+     * Possible values of this enum
+     */
+    const TRUE = 'true';
+    const FALSE = 'false';
+    
+    /**
+     * Gets allowable values of the enum
+     * @return string[]
+     */
+    public static function getAllowableEnumValues()
+    {
+        return [
+            self::TRUE,
+            self::FALSE,
+        ];
+    }
+}
+
+
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Capitalization.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Capitalization.php
index fbf65de7f75..aa49b66574d 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Capitalization.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Capitalization.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -384,6 +384,7 @@ public function setAttName($att_name)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -396,6 +397,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -409,6 +411,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -425,6 +428,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Cat.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Cat.php
index 6029e0ffd55..71d8589c83f 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Cat.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Cat.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -228,6 +228,7 @@ public function setDeclawed($declawed)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -240,6 +241,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -253,6 +255,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -269,6 +272,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Category.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Category.php
index 5a7416875f2..40f94dae4ef 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Category.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Category.php
@@ -13,12 +13,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -36,7 +36,6 @@
  * Category Class Doc Comment
  *
  * @category Class
- * @description A category for a pet
  * @package  Swagger\Client
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
@@ -265,6 +264,7 @@ public function setName($name)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -277,6 +277,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -290,6 +291,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -306,6 +308,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ClassModel.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ClassModel.php
index 32c18564255..d42cfc0925a 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ClassModel.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ClassModel.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -235,6 +235,7 @@ public function setClass($_class)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -247,6 +248,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -260,6 +262,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -276,6 +279,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Client.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Client.php
index c69e66abf91..0bd3cb11df5 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Client.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Client.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -234,6 +234,7 @@ public function setClient($client)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -246,6 +247,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -259,6 +261,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -275,6 +278,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Dog.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Dog.php
index a291dfc0310..17cfac809fb 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Dog.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Dog.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -228,6 +228,7 @@ public function setBreed($breed)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -240,6 +241,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -253,6 +255,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -269,6 +272,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumArrays.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumArrays.php
index 819caf87933..9d6edb75485 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumArrays.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumArrays.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -320,6 +320,7 @@ public function setArrayEnum($array_enum)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -332,6 +333,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -345,6 +347,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -361,6 +364,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumClass.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumClass.php
index e7e7c94c153..c5878e6d39c 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumClass.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumClass.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumTest.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumTest.php
index 146660c23fa..74effb4f178 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/EnumTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -489,6 +489,7 @@ public function setOuterEnum($outer_enum)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -501,6 +502,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -514,6 +516,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -530,6 +533,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/FormatTest.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/FormatTest.php
index 32f17e62537..e38d38430be 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/FormatTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/FormatTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -719,6 +719,7 @@ public function setPassword($password)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -731,6 +732,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -744,6 +746,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -760,6 +763,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/HasOnlyReadOnly.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/HasOnlyReadOnly.php
index 4cec0bd4d9a..b019619b179 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/HasOnlyReadOnly.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/HasOnlyReadOnly.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -264,6 +264,7 @@ public function setFoo($foo)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -276,6 +277,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -289,6 +291,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -305,6 +308,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/MapTest.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/MapTest.php
index 8d5e693736d..dbb87bc06d9 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/MapTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/MapTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -288,6 +288,7 @@ public function setMapOfEnumString($map_of_enum_string)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -300,6 +301,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -313,6 +315,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -329,6 +332,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/MixedPropertiesAndAdditionalPropertiesClass.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/MixedPropertiesAndAdditionalPropertiesClass.php
index 66bfc7162ea..8dbe448f32d 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/MixedPropertiesAndAdditionalPropertiesClass.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/MixedPropertiesAndAdditionalPropertiesClass.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -294,6 +294,7 @@ public function setMap($map)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -306,6 +307,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -319,6 +321,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -335,6 +338,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Model200Response.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Model200Response.php
index c3c8d7e28f9..2cfa077f844 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Model200Response.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Model200Response.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -265,6 +265,7 @@ public function setClass($class)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -277,6 +278,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -290,6 +292,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -306,6 +309,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelInterface.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelInterface.php
index 497546b0633..e1408238ba0 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelInterface.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelInterface.php
@@ -13,12 +13,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelList.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelList.php
index 6be35c1b746..375bf310e8a 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelList.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelList.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -234,6 +234,7 @@ public function set123List($_123_list)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -246,6 +247,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -259,6 +261,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -275,6 +278,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelReturn.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelReturn.php
index 12008802e64..e08e1912157 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelReturn.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ModelReturn.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -235,6 +235,7 @@ public function setReturn($return)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -247,6 +248,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -260,6 +262,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -276,6 +279,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Name.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Name.php
index e8ea7b79a6b..87705fcb6d8 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Name.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Name.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -328,6 +328,7 @@ public function set123Number($_123_number)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -340,6 +341,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -353,6 +355,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -369,6 +372,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/NumberOnly.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/NumberOnly.php
index 6652f04fc23..5dffecc0bcf 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/NumberOnly.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/NumberOnly.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -234,6 +234,7 @@ public function setJustNumber($just_number)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -246,6 +247,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -259,6 +261,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -275,6 +278,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Order.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Order.php
index 8abed8e858e..94569457d08 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Order.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Order.php
@@ -13,12 +13,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -36,7 +36,6 @@
  * Order Class Doc Comment
  *
  * @category Class
- * @description An order for a pets from the pet store
  * @package  Swagger\Client
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
@@ -419,6 +418,7 @@ public function setComplete($complete)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -431,6 +431,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -444,6 +445,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -460,6 +462,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterBoolean.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterBoolean.php
index da1371e3a49..fbbdccf8453 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterBoolean.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterBoolean.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -209,6 +209,7 @@ public function valid()
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -221,6 +222,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -234,6 +236,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -250,6 +253,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterComposite.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterComposite.php
index a1e5bdf9e07..6c23f38a72c 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterComposite.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterComposite.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -294,6 +294,7 @@ public function setMyBoolean($my_boolean)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -306,6 +307,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -319,6 +321,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -335,6 +338,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterEnum.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterEnum.php
index 3311c7fe705..79edabface6 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterEnum.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterEnum.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterNumber.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterNumber.php
index 6016808d6e8..3c2a1dc0640 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterNumber.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterNumber.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -209,6 +209,7 @@ public function valid()
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -221,6 +222,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -234,6 +236,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -250,6 +253,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterString.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterString.php
index e10da606d3a..311904480b9 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterString.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/OuterString.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -209,6 +209,7 @@ public function valid()
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -221,6 +222,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -234,6 +236,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -250,6 +253,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Pet.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Pet.php
index 2502e8b7e4d..a1769b5ec8a 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Pet.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Pet.php
@@ -13,12 +13,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -36,7 +36,6 @@
  * Pet Class Doc Comment
  *
  * @category Class
- * @description A pet for sale in the pet store
  * @package  Swagger\Client
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
@@ -425,6 +424,7 @@ public function setStatus($status)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -437,6 +437,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -450,6 +451,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -466,6 +468,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ReadOnlyFirst.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ReadOnlyFirst.php
index 6e116507205..9ac3e712bf7 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/ReadOnlyFirst.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/ReadOnlyFirst.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -264,6 +264,7 @@ public function setBaz($baz)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -276,6 +277,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -289,6 +291,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -305,6 +308,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/SpecialModelName.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/SpecialModelName.php
index e316c8d9b11..041ed270786 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/SpecialModelName.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/SpecialModelName.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -234,6 +234,7 @@ public function setSpecialPropertyName($special_property_name)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -246,6 +247,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -259,6 +261,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -275,6 +278,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Tag.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Tag.php
index 3e6025e6eba..3191571c350 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/Tag.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/Tag.php
@@ -13,12 +13,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -36,7 +36,6 @@
  * Tag Class Doc Comment
  *
  * @category Class
- * @description A tag for a pet
  * @package  Swagger\Client
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
@@ -265,6 +264,7 @@ public function setName($name)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -277,6 +277,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -290,6 +291,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -306,6 +308,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/Model/User.php b/samples/client/petstore/php/SwaggerClient-php/lib/Model/User.php
index 1f9ddd22b37..c2312b0b400 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/Model/User.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/Model/User.php
@@ -13,12 +13,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -36,7 +36,6 @@
  * User Class Doc Comment
  *
  * @category Class
- * @description A User who is purchasing from the pet store
  * @package  Swagger\Client
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
@@ -445,6 +444,7 @@ public function setUserStatus($user_status)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
         return isset($this->container[$offset]);
@@ -457,6 +457,7 @@ public function offsetExists($offset)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
@@ -470,6 +471,7 @@ public function offsetGet($offset)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
         if (is_null($offset)) {
@@ -486,6 +488,7 @@ public function offsetSet($offset, $value)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
         unset($this->container[$offset]);
diff --git a/samples/client/petstore/php/SwaggerClient-php/lib/ObjectSerializer.php b/samples/client/petstore/php/SwaggerClient-php/lib/ObjectSerializer.php
index c2148b2a923..5b613f84e6c 100644
--- a/samples/client/petstore/php/SwaggerClient-php/lib/ObjectSerializer.php
+++ b/samples/client/petstore/php/SwaggerClient-php/lib/ObjectSerializer.php
@@ -13,12 +13,12 @@
 /**
  * Swagger Petstore
  *
- * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
  *
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
diff --git a/samples/client/petstore/php/SwaggerClient-php/phpunit.xml.dist b/samples/client/petstore/php/SwaggerClient-php/phpunit.xml.dist
index cadedbc2469..c12ee148477 100644
--- a/samples/client/petstore/php/SwaggerClient-php/phpunit.xml.dist
+++ b/samples/client/petstore/php/SwaggerClient-php/phpunit.xml.dist
@@ -14,8 +14,8 @@
 
     <filter>
         <whitelist processUncoveredFilesFromWhitelist="true">
-            <directory suffix=".php">./lib\Api</directory>
-            <directory suffix=".php">./lib\Model</directory>
+            <directory suffix=".php">./lib/Api</directory>
+            <directory suffix=".php">./lib/Model</directory>
         </whitelist>
     </filter>
 </phpunit>
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Api/AnotherFakeApiTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Api/AnotherFakeApiTest.php
index 48c09a2ce97..ad4debd96e7 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Api/AnotherFakeApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Api/AnotherFakeApiTest.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -40,34 +40,34 @@
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
  */
-class AnotherFakeApiTest extends \PHPUnit_Framework_TestCase
+class AnotherFakeApiTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test cases
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Api/FakeApiTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Api/FakeApiTest.php
index dec5918dcba..cd52685ae75 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Api/FakeApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Api/FakeApiTest.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -40,34 +40,34 @@
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
  */
-class FakeApiTest extends \PHPUnit_Framework_TestCase
+class FakeApiTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test cases
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Api/FakeClassnameTags123ApiTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Api/FakeClassnameTags123ApiTest.php
index 5c1a24eb5c4..5a19bf9982f 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Api/FakeClassnameTags123ApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Api/FakeClassnameTags123ApiTest.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -40,34 +40,34 @@
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
  */
-class FakeClassnameTags123ApiTest extends \PHPUnit_Framework_TestCase
+class FakeClassnameTags123ApiTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test cases
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Api/PetApiTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Api/PetApiTest.php
index 892e30c3171..ca98966f580 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Api/PetApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Api/PetApiTest.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -40,34 +40,34 @@
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
  */
-class PetApiTest extends \PHPUnit_Framework_TestCase
+class PetApiTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test cases
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Api/StoreApiTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Api/StoreApiTest.php
index c186432170e..bf130507bf2 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Api/StoreApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Api/StoreApiTest.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -40,34 +40,34 @@
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
  */
-class StoreApiTest extends \PHPUnit_Framework_TestCase
+class StoreApiTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test cases
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Api/UserApiTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Api/UserApiTest.php
index 822e6b84b7f..fe609dd8965 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Api/UserApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Api/UserApiTest.php
@@ -17,7 +17,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -40,34 +40,34 @@
  * @author   Swagger Codegen team
  * @link     https://github.com/swagger-api/swagger-codegen
  */
-class UserApiTest extends \PHPUnit_Framework_TestCase
+class UserApiTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test cases
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/AdditionalPropertiesClassTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/AdditionalPropertiesClassTest.php
index 8ffddf14cc9..a359ea0b8c8 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/AdditionalPropertiesClassTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/AdditionalPropertiesClassTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class AdditionalPropertiesClassTest extends \PHPUnit_Framework_TestCase
+class AdditionalPropertiesClassTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/AnimalFarmTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/AnimalFarmTest.php
index 69f3552d76b..ad464737a86 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/AnimalFarmTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/AnimalFarmTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class AnimalFarmTest extends \PHPUnit_Framework_TestCase
+class AnimalFarmTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/AnimalTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/AnimalTest.php
index 9e640ebe0fe..93eea76ceeb 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/AnimalTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/AnimalTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class AnimalTest extends \PHPUnit_Framework_TestCase
+class AnimalTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/ApiResponseTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/ApiResponseTest.php
index d4a63e88b34..e7089cf7830 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/ApiResponseTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/ApiResponseTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ApiResponseTest extends \PHPUnit_Framework_TestCase
+class ApiResponseTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayOfArrayOfNumberOnlyTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayOfArrayOfNumberOnlyTest.php
index 779186ca795..32aa3ccf7be 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayOfArrayOfNumberOnlyTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayOfArrayOfNumberOnlyTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ArrayOfArrayOfNumberOnlyTest extends \PHPUnit_Framework_TestCase
+class ArrayOfArrayOfNumberOnlyTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayOfNumberOnlyTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayOfNumberOnlyTest.php
index 332a1d8988a..51beb225876 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayOfNumberOnlyTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayOfNumberOnlyTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ArrayOfNumberOnlyTest extends \PHPUnit_Framework_TestCase
+class ArrayOfNumberOnlyTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayTestTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayTestTest.php
index d9e06a9b584..61e4a8970a3 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayTestTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/ArrayTestTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ArrayTestTest extends \PHPUnit_Framework_TestCase
+class ArrayTestTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/BooleanTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/BooleanTest.php
new file mode 100644
index 00000000000..6cdd5ce2eb4
--- /dev/null
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/BooleanTest.php
@@ -0,0 +1,78 @@
+<?php
+/**
+ * BooleanTest
+ *
+ * PHP version 5
+ *
+ * @category Class
+ * @package  Swagger\Client
+ * @author   Swagger Codegen team
+ * @link     https://github.com/swagger-api/swagger-codegen
+ */
+
+/**
+ * Swagger Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * OpenAPI spec version: 1.0.0
+ * Contact: apiteam@swagger.io
+ * Generated by: https://github.com/swagger-api/swagger-codegen.git
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
+ */
+
+/**
+ * NOTE: This class is auto generated by the swagger code generator program.
+ * https://github.com/swagger-api/swagger-codegen
+ * Please update the test case below to test the model.
+ */
+
+namespace Swagger\Client;
+
+/**
+ * BooleanTest Class Doc Comment
+ *
+ * @category    Class
+ * @description True or False indicator
+ * @package     Swagger\Client
+ * @author      Swagger Codegen team
+ * @link        https://github.com/swagger-api/swagger-codegen
+ */
+class BooleanTest extends \PHPUnit\Framework\TestCase
+{
+
+    /**
+     * Setup before running any test case
+     */
+    public static function setUpBeforeClass(): void
+    {
+    }
+
+    /**
+     * Setup before running each test case
+     */
+    public function setUp(): void
+    {
+    }
+
+    /**
+     * Clean up after running each test case
+     */
+    public function tearDown(): void
+    {
+    }
+
+    /**
+     * Clean up after running all test cases
+     */
+    public static function tearDownAfterClass(): void
+    {
+    }
+
+    /**
+     * Test "Boolean"
+     */
+    public function testBoolean()
+    {
+    }
+}
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/CapitalizationTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/CapitalizationTest.php
index 9d423c9c449..b0215517ebb 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/CapitalizationTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/CapitalizationTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class CapitalizationTest extends \PHPUnit_Framework_TestCase
+class CapitalizationTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/CatTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/CatTest.php
index a87e606d04d..716217efe1a 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/CatTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/CatTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class CatTest extends \PHPUnit_Framework_TestCase
+class CatTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/CategoryTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/CategoryTest.php
index 0cad2dfe70d..54f05ca402b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/CategoryTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/CategoryTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class CategoryTest extends \PHPUnit_Framework_TestCase
+class CategoryTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/ClassModelTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/ClassModelTest.php
index 4f8811d3e49..b6dff95461c 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/ClassModelTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/ClassModelTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ClassModelTest extends \PHPUnit_Framework_TestCase
+class ClassModelTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/ClientTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/ClientTest.php
index b35c695a515..facdcadf612 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/ClientTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/ClientTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ClientTest extends \PHPUnit_Framework_TestCase
+class ClientTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/DogTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/DogTest.php
index 677dcb3f119..0abe76906e2 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/DogTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/DogTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class DogTest extends \PHPUnit_Framework_TestCase
+class DogTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumArraysTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumArraysTest.php
index eb5ba74a0eb..2e4b15347d3 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumArraysTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumArraysTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class EnumArraysTest extends \PHPUnit_Framework_TestCase
+class EnumArraysTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumClassTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumClassTest.php
index 23b9e9816ff..79ae9b2fae8 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumClassTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumClassTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class EnumClassTest extends \PHPUnit_Framework_TestCase
+class EnumClassTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumTestTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumTestTest.php
index a5c10cd253f..33e0be83f8c 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumTestTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/EnumTestTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class EnumTestTest extends \PHPUnit_Framework_TestCase
+class EnumTestTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/FormatTestTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/FormatTestTest.php
index c41eb281824..ef211a8416b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/FormatTestTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/FormatTestTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class FormatTestTest extends \PHPUnit_Framework_TestCase
+class FormatTestTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/HasOnlyReadOnlyTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/HasOnlyReadOnlyTest.php
index bccf9d2862e..a6eeeba6bd0 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/HasOnlyReadOnlyTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/HasOnlyReadOnlyTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class HasOnlyReadOnlyTest extends \PHPUnit_Framework_TestCase
+class HasOnlyReadOnlyTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/MapTestTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/MapTestTest.php
index 6b85eb1d7d0..9aaf23dabf0 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/MapTestTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/MapTestTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class MapTestTest extends \PHPUnit_Framework_TestCase
+class MapTestTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/MixedPropertiesAndAdditionalPropertiesClassTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/MixedPropertiesAndAdditionalPropertiesClassTest.php
index 00fd88f1040..348dd266239 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/MixedPropertiesAndAdditionalPropertiesClassTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/MixedPropertiesAndAdditionalPropertiesClassTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class MixedPropertiesAndAdditionalPropertiesClassTest extends \PHPUnit_Framework_TestCase
+class MixedPropertiesAndAdditionalPropertiesClassTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/Model200ResponseTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/Model200ResponseTest.php
index 2c1a3ab4039..585d6bffed9 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/Model200ResponseTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/Model200ResponseTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class Model200ResponseTest extends \PHPUnit_Framework_TestCase
+class Model200ResponseTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/ModelListTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/ModelListTest.php
index 3b130b6c907..68764daa5ab 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/ModelListTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/ModelListTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ModelListTest extends \PHPUnit_Framework_TestCase
+class ModelListTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/ModelReturnTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/ModelReturnTest.php
index 1b5fe24f8f2..23f8dcda352 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/ModelReturnTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/ModelReturnTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ModelReturnTest extends \PHPUnit_Framework_TestCase
+class ModelReturnTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/NameTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/NameTest.php
index f63e5d70bba..786757aa574 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/NameTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/NameTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class NameTest extends \PHPUnit_Framework_TestCase
+class NameTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/NumberOnlyTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/NumberOnlyTest.php
index e27bf391e67..0c0b9b16363 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/NumberOnlyTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/NumberOnlyTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class NumberOnlyTest extends \PHPUnit_Framework_TestCase
+class NumberOnlyTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/OrderTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/OrderTest.php
index 8221fc219a2..71537476fbb 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/OrderTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/OrderTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class OrderTest extends \PHPUnit_Framework_TestCase
+class OrderTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterBooleanTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterBooleanTest.php
index fca1ce87a2c..1f6d8247dd7 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterBooleanTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterBooleanTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class OuterBooleanTest extends \PHPUnit_Framework_TestCase
+class OuterBooleanTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterCompositeTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterCompositeTest.php
index 20b7cba2071..04d6ad7149b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterCompositeTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterCompositeTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class OuterCompositeTest extends \PHPUnit_Framework_TestCase
+class OuterCompositeTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterEnumTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterEnumTest.php
index 72948843d4d..3a16d2e13c6 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterEnumTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterEnumTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class OuterEnumTest extends \PHPUnit_Framework_TestCase
+class OuterEnumTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterNumberTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterNumberTest.php
index 781630d5f4a..e3498e67403 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterNumberTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterNumberTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class OuterNumberTest extends \PHPUnit_Framework_TestCase
+class OuterNumberTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterStringTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterStringTest.php
index 1f05e30f06b..a9029589e3a 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterStringTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/OuterStringTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class OuterStringTest extends \PHPUnit_Framework_TestCase
+class OuterStringTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/PetTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/PetTest.php
index d3e72e937bd..949271fd22b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/PetTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/PetTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class PetTest extends \PHPUnit_Framework_TestCase
+class PetTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/ReadOnlyFirstTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/ReadOnlyFirstTest.php
index 6c828e89a28..4511f826b91 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/ReadOnlyFirstTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/ReadOnlyFirstTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class ReadOnlyFirstTest extends \PHPUnit_Framework_TestCase
+class ReadOnlyFirstTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/SpecialModelNameTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/SpecialModelNameTest.php
index 9ead0368683..c2bde93aa11 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/SpecialModelNameTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/SpecialModelNameTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class SpecialModelNameTest extends \PHPUnit_Framework_TestCase
+class SpecialModelNameTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/TagTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/TagTest.php
index 347177fe24b..2cb470e1692 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/TagTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/TagTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class TagTest extends \PHPUnit_Framework_TestCase
+class TagTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/test/Model/UserTest.php b/samples/client/petstore/php/SwaggerClient-php/test/Model/UserTest.php
index d9526b27aee..97fd2c4c5c7 100644
--- a/samples/client/petstore/php/SwaggerClient-php/test/Model/UserTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/test/Model/UserTest.php
@@ -18,7 +18,7 @@
  * OpenAPI spec version: 1.0.0
  * Contact: apiteam@swagger.io
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
- * Swagger Codegen version: 2.4.3-SNAPSHOT
+ * Swagger Codegen version: 2.4.53-SNAPSHOT
  */
 
 /**
@@ -38,34 +38,34 @@
  * @author      Swagger Codegen team
  * @link        https://github.com/swagger-api/swagger-codegen
  */
-class UserTest extends \PHPUnit_Framework_TestCase
+class UserTest extends \PHPUnit\Framework\TestCase
 {
 
     /**
      * Setup before running any test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
     }
 
     /**
      * Setup before running each test case
      */
-    public function setUp()
+    public function setUp(): void
     {
     }
 
     /**
      * Clean up after running each test case
      */
-    public function tearDown()
+    public function tearDown(): void
     {
     }
 
     /**
      * Clean up after running all test cases
      */
-    public static function tearDownAfterClass()
+    public static function tearDownAfterClass(): void
     {
     }
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/AsyncTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/AsyncTest.php
index 049869c357d..b7564933784 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/AsyncTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/AsyncTest.php
@@ -5,7 +5,7 @@
 use Swagger\Client\Api\PetApi;
 use Swagger\Client\Model\Pet;
 
-class AsyncTest extends \PHPUnit_Framework_TestCase
+class AsyncTest extends \PHPUnit\Framework\TestCase
 {
     /** @var PetApi */
     private $api;
@@ -13,7 +13,7 @@ class AsyncTest extends \PHPUnit_Framework_TestCase
     /** @var  int */
     private $petId;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->api = new Api\PetApi();
 
@@ -57,13 +57,13 @@ public function testAsyncRequestWithHttpInfo()
 
         list($pet, $status, $headers) = $promise->wait();
         $this->assertEquals(200, $status);
-        $this->assertInternalType('array', $headers);
+        $this->assertIsArray($headers);
         $this->assertInstanceOf(Pet::class, $pet);
     }
 
     public function testAsyncThrowingException()
     {
-        $this->setExpectedException(ApiException::class);
+        $this->expectException(ApiException::class);
 
         $promise = $this->api->getPetByIdAsync(0);
         $promise->wait();
@@ -77,7 +77,7 @@ public function testAsyncApiExceptionWithoutWaitIsNotThrown()
 
     public function testAsyncHttpInfoThrowingException()
     {
-        $this->setExpectedException(ApiException::class);
+        $this->expectException(ApiException::class);
 
         $promise = $this->api->getPetByIdAsyncWithHttpInfo(0);
         $promise->wait();
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/AuthTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/AuthTest.php
index d0204352558..1ba3624651f 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/AuthTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/AuthTest.php
@@ -8,7 +8,7 @@
 
 require_once __DIR__ . '/FakeHttpClient.php';
 
-class AuthTest extends \PHPUnit_Framework_TestCase
+class AuthTest extends \PHPUnit\Framework\TestCase
 {
     public function testCustomApiKeyHeader()
     {
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/DateTimeSerializerTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/DateTimeSerializerTest.php
index cea8db4a067..75f122666dc 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/DateTimeSerializerTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/DateTimeSerializerTest.php
@@ -4,7 +4,7 @@
 
 use Swagger\Client\Model\FormatTest;
 
-class DateTimeSerializerTest extends \PHPUnit_Framework_TestCase
+class DateTimeSerializerTest extends \PHPUnit\Framework\TestCase
 {
     public function testDateTimeSanitazion()
     {
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/DebugTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/DebugTest.php
index 6eb9dacaffe..6395b1b0e7b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/DebugTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/DebugTest.php
@@ -1,7 +1,7 @@
 <?php
 namespace Swagger\Client;
 
-class DebugTest extends \PHPUnit_Framework_TestCase
+class DebugTest extends \PHPUnit\Framework\TestCase
 {
     public function testEnableDebugOutput()
     {
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/EnumClassTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/EnumClassTest.php
index 7ba9d0552bb..82c2fbb1e5b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/EnumClassTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/EnumClassTest.php
@@ -4,7 +4,7 @@
 
 use Swagger\Client\Model\EnumClass;
 
-class EnumClassTest extends \PHPUnit_Framework_TestCase
+class EnumClassTest extends \PHPUnit\Framework\TestCase
 {
     public function testPossibleValues()
     {
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/EnumTestTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/EnumTestTest.php
index 834c4703104..419d7e747f7 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/EnumTestTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/EnumTestTest.php
@@ -4,7 +4,7 @@
 
 use Swagger\Client\Model\EnumTest;
 
-class EnumTestTest extends \PHPUnit_Framework_TestCase
+class EnumTestTest extends \PHPUnit\Framework\TestCase
 {
     public function testPossibleValues()
     {
@@ -31,11 +31,9 @@ public function testStrictValidation()
         $this->assertSame($expected, $enum->listInvalidProperties());
     }
 
-    /**
-     * @expectedException \InvalidArgumentException
-     */
     public function testThrowExceptionWhenInvalidAmbiguousValueHasPassed()
     {
+        $this->expectException(\InvalidArgumentException::class);
         $enum = new EnumTest();
         $enum->setEnumString(0);
     }
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/ExceptionTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/ExceptionTest.php
index 29a0d5d7559..acb0c2bb59b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/ExceptionTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/ExceptionTest.php
@@ -4,15 +4,13 @@
 
 use GuzzleHttp\Client;
 
-class ExceptionTest extends \PHPUnit_Framework_TestCase
+class ExceptionTest extends \PHPUnit\Framework\TestCase
 {
-    /**
-     * @expectedException \Swagger\Client\ApiException
-     * @expectedExceptionCode 404
-     * @expectedExceptionMessage http://petstore.swagger.io/INVALID_URL/store/inventory
-     */
     public function testNotFound()
     {
+        $this->expectException(\Swagger\Client\ApiException::class);
+        $this->expectExceptionCode(404);
+        $this->expectExceptionMessage('http://petstore.swagger.io/INVALID_URL/store/inventory');
         $config = new Configuration();
         $config->setHost('http://petstore.swagger.io/INVALID_URL');
 
@@ -23,12 +21,10 @@ public function testNotFound()
         $api->getInventory();
     }
 
-    /**
-     * @expectedException \Swagger\Client\ApiException
-     * @expectedExceptionMessage Could not resolve host
-     */
     public function testWrongHost()
     {
+        $this->expectException(\Swagger\Client\ApiException::class);
+        $this->expectExceptionMessage('Could not resolve host');
         $config = new Configuration();
         $config->setHost('http://wrong_host.zxc');
 
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/FakeHttpClient.php b/samples/client/petstore/php/SwaggerClient-php/tests/FakeHttpClient.php
index abdfa7cf7c2..774ba5a5f4f 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/FakeHttpClient.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/FakeHttpClient.php
@@ -4,6 +4,7 @@
 
 use GuzzleHttp\ClientInterface;
 use GuzzleHttp\Exception\GuzzleException;
+use GuzzleHttp\Promise\PromiseInterface;
 use GuzzleHttp\Psr7\Response;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
@@ -26,7 +27,7 @@ public function getLastRequest()
     /**
      * @param null|ResponseInterface $response
      */
-    public function setResponse(ResponseInterface $response = null)
+    public function setResponse(?ResponseInterface $response = null)
     {
         $this->response = $response;
     }
@@ -41,23 +42,23 @@ public function setResponse(ResponseInterface $response = null)
      * @return ResponseInterface
      * @throws GuzzleException
      */
-    public function send(RequestInterface $request, array $options = [])
+    public function send(RequestInterface $request, array $options = []): ResponseInterface
     {
         $this->request = $request;
         return $this->response ?: new Response(200);
     }
 
-    public function sendAsync(RequestInterface $request, array $options = [])
+    public function sendAsync(RequestInterface $request, array $options = []): PromiseInterface
     {
         throw new \RuntimeException('not implemented');
     }
 
-    public function request($method, $uri, array $options = [])
+    public function request(string $method, $uri, array $options = []): ResponseInterface
     {
         throw new \RuntimeException('not implemented');
     }
 
-    public function requestAsync($method, $uri, array $options = [])
+    public function requestAsync(string $method, $uri, array $options = []): PromiseInterface
     {
         throw new \RuntimeException('not implemented');
     }
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/FormatTestTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/FormatTestTest.php
index e91222a1686..2e8ced07561 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/FormatTestTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/FormatTestTest.php
@@ -2,7 +2,7 @@
 
 use Swagger\Client\Model\FormatTest;
 
-class FormatTestTest extends \PHPUnit_Framework_TestCase
+class FormatTestTest extends \PHPUnit\Framework\TestCase
 {
     public function testCountTheLengthOfMultiByteStringsCorrectly()
     {
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/HeaderSelectorTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/HeaderSelectorTest.php
index 7a89448f89e..eaf4958544d 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/HeaderSelectorTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/HeaderSelectorTest.php
@@ -2,7 +2,7 @@
 
 namespace Swagger\Client;
 
-class HeaderSelectorTest extends \PHPUnit_Framework_TestCase
+class HeaderSelectorTest extends \PHPUnit\Framework\TestCase
 {
     public function testSelectingHeaders()
     {
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/HeadersTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/HeadersTest.php
index 5431a912efe..a3dc4c96ce8 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/HeadersTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/HeadersTest.php
@@ -4,12 +4,12 @@
 
 require_once __DIR__ . '/FakeHttpClient.php';
 
-class HeadersTest extends \PHPUnit_Framework_TestCase
+class HeadersTest extends \PHPUnit\Framework\TestCase
 {
     /** @var  FakeHttpClient */
     private $fakeHttpClient;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->fakeHttpClient = new FakeHttpClient();
     }
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/ModelInheritanceTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/ModelInheritanceTest.php
index 658e60ba638..4b8fc4a2d73 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/ModelInheritanceTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/ModelInheritanceTest.php
@@ -12,7 +12,7 @@
  *
  * @package Swagger\Client
  */
-class ModelInheritanceTest extends \PHPUnit_Framework_TestCase
+class ModelInheritanceTest extends \PHPUnit\Framework\TestCase
 {
     /**
      * test if default values works
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/ObjectSerializerTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/ObjectSerializerTest.php
index e81f5b03fc2..3dfb13b669b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/ObjectSerializerTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/ObjectSerializerTest.php
@@ -3,7 +3,7 @@
 namespace Swagger\Client;
 
 // test object serializer
-class ObjectSerializerTest extends \PHPUnit_Framework_TestCase
+class ObjectSerializerTest extends \PHPUnit\Framework\TestCase
 {
     /**
      * Test the sanitizeForSerialization method with a stdClass.
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/OrderApiTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/OrderApiTest.php
index 8b5c8f7e499..2ca4c30c77b 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/OrderApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/OrderApiTest.php
@@ -2,11 +2,11 @@
 
 namespace Swagger\Client;
 
-class OrderApiTest extends \PHPUnit_Framework_TestCase
+class OrderApiTest extends \PHPUnit\Framework\TestCase
 {
 
     // add a new pet (id 10005) to ensure the pet object is available for all the tests
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
         // for error reporting (need to run with php5.3 to get no warning)
         //ini_set('display_errors', 1);
@@ -30,11 +30,9 @@ public function testOrder()
         $this->assertSame("placed", $order->getStatus());
     }
  
-    /**
-     * @expectedException InvalidArgumentException
-     */
     public function testOrderException()
     {
+        $this->expectException(\InvalidArgumentException::class);
         // initialize the API client
         $order = new Model\Order();
         $order->setStatus("invalid_value");
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/OuterEnumTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/OuterEnumTest.php
index d7d12d5cbb8..5a9581f104c 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/OuterEnumTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/OuterEnumTest.php
@@ -5,7 +5,7 @@
 use Swagger\Client\Model\EnumTest;
 use Swagger\Client\Model\OuterEnum;
 
-class OuterEnumTest extends \PHPUnit_Framework_TestCase
+class OuterEnumTest extends \PHPUnit\Framework\TestCase
 {
     public function testDeserialize()
     {
@@ -14,13 +14,13 @@ public function testDeserialize()
             OuterEnum::class
         );
 
-        $this->assertInternalType('string', $result);
+        $this->assertIsString($result);
         $this->assertEquals('placed', $result);
     }
 
     public function testDeserializeInvalidValue()
     {
-        $this->setExpectedException(\InvalidArgumentException::class, 'Invalid value for enum');
+        $this->expectException(\InvalidArgumentException::class); $this->expectExceptionMessage('Invalid value for enum');
 
         ObjectSerializer::deserialize(
             "lkjfalgkdfjg",
@@ -55,7 +55,7 @@ public function testSanitize()
             $json
         );
 
-        $this->assertInternalType('string', $result);
+        $this->assertIsString($result);
     }
 
     public function testSanitizeNested()
@@ -71,16 +71,16 @@ public function testSanitizeNested()
             $input
         );
 
-        $this->assertInternalType('object', $result);
+        $this->assertIsObject($result);
         $this->assertInstanceOf(\stdClass::class, $result);
 
-        $this->assertInternalType('string', $result->outerEnum);
+        $this->assertIsString($result->outerEnum);
         $this->assertEquals('approved', $result->outerEnum);
     }
 
     public function testSanitizeNestedInvalidValue()
     {
-        $this->setExpectedException(\InvalidArgumentException::class, 'Invalid value for enum');
+        $this->expectException(\InvalidArgumentException::class); $this->expectExceptionMessage('Invalid value for enum');
 
         $input = new EnumTest([
             'enum_string' => 'UPPER',
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/ParametersTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/ParametersTest.php
index 37877556d01..e5dc3fcaa49 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/ParametersTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/ParametersTest.php
@@ -7,7 +7,7 @@
 
 require_once __DIR__ . '/FakeHttpClient.php';
 
-class ParametersTest extends \PHPUnit_Framework_TestCase
+class ParametersTest extends \PHPUnit\Framework\TestCase
 {
     /** @var  FakeHttpClient */
     private $fakeHttpClient;
@@ -16,7 +16,7 @@ class ParametersTest extends \PHPUnit_Framework_TestCase
     /** @var  UserApi */
     private $userApi;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->fakeHttpClient = new FakeHttpClient();
         $this->fakeApi = new Api\FakeApi($this->fakeHttpClient);
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/PetApiTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/PetApiTest.php
index 1cfad6aaeae..46f5e962c2c 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/PetApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/PetApiTest.php
@@ -6,14 +6,14 @@
 use Swagger\Client\Model\ApiResponse;
 use Swagger\Client\Model\Pet;
 
-class PetApiTest extends \PHPUnit_Framework_TestCase
+class PetApiTest extends \PHPUnit\Framework\TestCase
 {
 
     /** @var  PetApi */
     private $api;
 
     // add a new pet (id 10005) to ensure the pet object is available for all the tests
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
         // increase memory limit to avoid fatal error due to findPetByStatus
         // returning a lot of data
@@ -45,10 +45,10 @@ public static function setUpBeforeClass()
 
         // add a new pet (model)
         list(, $status) = $petApi->addPetWithHttpInfo($newPet);
-        \PHPUnit_Framework_Assert::assertEquals(200, $status);
+        \PHPUnit\Framework\Assert::assertEquals(200, $status);
     }
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->api = new Api\PetApi();
     }
@@ -86,7 +86,7 @@ public function testGetPetById()
      * $this->assertSame($response->getPhotoUrls()[0], 'http://test_php_unit_test.com');
      *
      * // category is type "object"
-     * $this->assertInternalType('array', $response->getCategory());
+     * $this->assertIsArray($response->getCategory());
      * $this->assertSame($response->getCategory()['id'], $pet_id);
      * $this->assertSame($response->getCategory()['name'], 'test php category');
      *
@@ -278,7 +278,7 @@ public function testGetPetByIdWithByteArray()
         $bytes = $pet_api->petPetIdtestingByteArraytrueGet($pet_id);
         $json = json_decode($bytes, true);
 
-        $this->assertInternalType("string", $bytes);
+        $this->assertIsString($bytes);
 
         $this->assertSame($json['id'], $pet_id);
         // not testing name as it's tested by addPetUsingByteArray
@@ -375,12 +375,11 @@ public function testDefaultValues()
 
     /**
      * test invalid argument
-     *
-     * @expectedException \InvalidArgumentException
-     * @expectedExceptionMessage Missing the required parameter $status when calling findPetsByStatus
      */
     public function testInvalidArgument()
     {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Missing the required parameter $status when calling findPetsByStatus');
         // the argument is required, and we must specify one or some from 'available', 'pending', 'sold'
         $this->api->findPetsByStatus([]);
     }
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/PetTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/PetTest.php
index 60ce604c522..7ddb44622ca 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/PetTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/PetTest.php
@@ -4,7 +4,7 @@
 
 use Swagger\Client\Model\Pet;
 
-class PetTest extends \PHPUnit_Framework_TestCase
+class PetTest extends \PHPUnit\Framework\TestCase
 {
     /**
      * test empty object serialization
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/RequestTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/RequestTest.php
index 779ae71ab02..66a89df974a 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/RequestTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/RequestTest.php
@@ -4,7 +4,7 @@
 
 use Swagger\Client\Api\FakeApi;
 
-class RequestTest extends \PHPUnit_Framework_TestCase
+class RequestTest extends \PHPUnit\Framework\TestCase
 {
 
     /** @var FakeApi */
@@ -12,7 +12,7 @@ class RequestTest extends \PHPUnit_Framework_TestCase
     /** @var  FakeHttpClient */
     private $fakeClient;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->fakeClient = new FakeHttpClient();
         $this->api = new Api\FakeApi($this->fakeClient);
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/ResponseTypesTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/ResponseTypesTest.php
index 71eda338ba9..6b2257e5073 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/ResponseTypesTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/ResponseTypesTest.php
@@ -8,14 +8,14 @@
 
 require_once __DIR__ . '/FakeHttpClient.php';
 
-class ResponseTypesTest extends \PHPUnit_Framework_TestCase
+class ResponseTypesTest extends \PHPUnit\Framework\TestCase
 {
     /** @var PetApi */
     private $api;
     /** @var  FakeHttpClient */
     private $fakeHttpClient;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->fakeHttpClient = new FakeHttpClient();
         $this->api = new PetApi($this->fakeHttpClient);
@@ -37,12 +37,10 @@ public function testDefault2xxReturnType()
         $this->assertInstanceOf(Pet::class, $result);
     }
 
-    /**
-     * @expectedException \Swagger\Client\ApiException
-     * @expectedExceptionCode 400
-     */
     public function testDefinedErrorException()
     {
+        $this->expectException(\Swagger\Client\ApiException::class);
+        $this->expectExceptionCode(400);
         $statusCode = 400;
 
         $this->fakeHttpClient->setResponse(new Response($statusCode, [], '{}'));
@@ -68,12 +66,10 @@ public function testDefinedErrorException()
 //        $this->assertInstanceOf(Error::class, $result);
 //    }
 
-    /**
-     * @expectedException \Swagger\Client\ApiException
-     * @expectedExceptionCode 404
-     */
     public function testDefaultErrorException()
     {
+        $this->expectException(\Swagger\Client\ApiException::class);
+        $this->expectExceptionCode(404);
         $statusCode = 404;
 
         $this->fakeHttpClient->setResponse(new Response($statusCode, [], '{}'));
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/StoreApiTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/StoreApiTest.php
index 3af84b8d851..6be4d931bee 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/StoreApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/StoreApiTest.php
@@ -8,12 +8,12 @@
 use Swagger\Client\Model\Pet;
 use Swagger\Client\Model\Tag;
 
-class StoreApiTest extends \PHPUnit_Framework_TestCase
+class StoreApiTest extends \PHPUnit\Framework\TestCase
 {
     /** @var  StoreApi */
     private $api;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->api = new StoreApi();
     }
@@ -21,7 +21,7 @@ public function setUp()
     /**
      * Setup before running each test case
      */
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
     {
         // add a new pet (id 10005) to ensure the pet object is available for all the tests
         // new pet
@@ -50,7 +50,7 @@ public function testGetInventory()
     {
         $result = $this->api->getInventory();
 
-        $this->assertInternalType('array', $result);
-        $this->assertInternalType('int', $result['available']);
+        $this->assertIsArray($result);
+        $this->assertIsInt($result['available']);
     }
 }
diff --git a/samples/client/petstore/php/SwaggerClient-php/tests/UserApiTest.php b/samples/client/petstore/php/SwaggerClient-php/tests/UserApiTest.php
index fdaf42467e1..9283c6e7337 100644
--- a/samples/client/petstore/php/SwaggerClient-php/tests/UserApiTest.php
+++ b/samples/client/petstore/php/SwaggerClient-php/tests/UserApiTest.php
@@ -4,13 +4,13 @@
 
 use Swagger\Client\Api\UserApi;
 
-class UserApiTest extends \PHPUnit_Framework_TestCase
+class UserApiTest extends \PHPUnit\Framework\TestCase
 {
 
     /** @var UserApi*/
     private $api;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->api = new Api\UserApi();
     }
@@ -22,7 +22,7 @@ public function testLoginUser()
         // login
         $response = $this->api->loginUser('xxxxx', 'yyyyyyyy');
         
-        $this->assertInternalType('string', $response);
+        $this->assertIsString($response);
         $this->assertRegExp(
             '/logged in user session/',
             $response,
diff --git a/samples/server/petstore/php-symfony/.swagger-codegen/VERSION b/samples/server/petstore/php-symfony/.swagger-codegen/VERSION
index 0e6df709793..bab531eaf33 100644
--- a/samples/server/petstore/php-symfony/.swagger-codegen/VERSION
+++ b/samples/server/petstore/php-symfony/.swagger-codegen/VERSION
@@ -1 +1 @@
-2.4.5-SNAPSHOT
\ No newline at end of file
+2.4.53-SNAPSHOT
\ No newline at end of file
diff --git a/samples/server/petstore/php-symfony/SymfonyBundle-php/composer.json b/samples/server/petstore/php-symfony/SymfonyBundle-php/composer.json
index 1834f482225..2001aa4aa19 100644
--- a/samples/server/petstore/php-symfony/SymfonyBundle-php/composer.json
+++ b/samples/server/petstore/php-symfony/SymfonyBundle-php/composer.json
@@ -27,7 +27,7 @@
     "require-dev": {
         "phpunit/phpunit": "~4.8",
         "satooshi/php-coveralls": "~1.0",
-        "squizlabs/php_codesniffer": "~2.6",
+        "squizlabs/php_codesniffer": "^3.0",
         "friendsofphp/php-cs-fixer": "~1.12",
         "symfony/browser-kit": "*",
         "hoa/regex": "~1.0"