diff --git a/modules/openapi-generator/src/main/resources/php-nextgen/ApiException.mustache b/modules/openapi-generator/src/main/resources/php-nextgen/ApiException.mustache
index 31766db08e7..6720e351fb7 100644
--- a/modules/openapi-generator/src/main/resources/php-nextgen/ApiException.mustache
+++ b/modules/openapi-generator/src/main/resources/php-nextgen/ApiException.mustache
@@ -39,7 +39,7 @@ class ApiException extends Exception
     /**
      * The HTTP header of the server response.
      *
-     * @var string[]|null
+     * @var string[][]|null
      */
     protected ?array $responseHeaders;
 
@@ -55,10 +55,10 @@ class ApiException extends Exception
      *
      * @param string                $message         Error message
      * @param int                   $code            HTTP status code
-     * @param string[]|null         $responseHeaders HTTP response header
-     * @param mixed $responseBody    HTTP decoded body of the server response either as stdClass or string
+     * @param string[][]|null       $responseHeaders HTTP response header
+     * @param stdClass|string|null  $responseBody    HTTP decoded body of the server response either as stdClass or string
      */
-    public function __construct(string $message = "", int $code = 0, ?array $responseHeaders = [], mixed $responseBody = null)
+    public function __construct(string $message = "", int $code = 0, ?array $responseHeaders = [], stdClass|string|null $responseBody = null)
     {
         parent::__construct($message, $code);
         $this->responseHeaders = $responseHeaders;
@@ -68,7 +68,7 @@ class ApiException extends Exception
     /**
      * Gets the HTTP response header
      *
-     * @return string[]|null HTTP response header
+     * @return string[][]|null HTTP response header
      */
     public function getResponseHeaders(): ?array
     {
diff --git a/modules/openapi-generator/src/main/resources/php/ApiException.mustache b/modules/openapi-generator/src/main/resources/php/ApiException.mustache
index e9d6544b21c..c5c3995dd54 100644
--- a/modules/openapi-generator/src/main/resources/php/ApiException.mustache
+++ b/modules/openapi-generator/src/main/resources/php/ApiException.mustache
@@ -40,7 +40,7 @@ class ApiException extends Exception
     /**
      * The HTTP header of the server response.
      *
-     * @var string[]|null
+     * @var string[][]|null
      */
     protected $responseHeaders;
 
@@ -56,7 +56,7 @@ class ApiException extends Exception
      *
      * @param string                $message         Error message
      * @param int                   $code            HTTP status code
-     * @param string[]|null         $responseHeaders HTTP response header
+     * @param string[][]|null       $responseHeaders HTTP response header
      * @param \stdClass|string|null $responseBody    HTTP decoded body of the server response either as \stdClass or string
      */
     public function __construct($message = "", $code = 0, $responseHeaders = [], $responseBody = null)
@@ -69,7 +69,7 @@ class ApiException extends Exception
     /**
      * Gets the HTTP response header
      *
-     * @return string[]|null HTTP response header
+     * @return string[][]|null HTTP response header
      */
     public function getResponseHeaders()
     {
diff --git a/modules/openapi-generator/src/main/resources/php/libraries/psr-18/ApiException.mustache b/modules/openapi-generator/src/main/resources/php/libraries/psr-18/ApiException.mustache
index 5a96f2f6f5a..83aaec422dd 100644
--- a/modules/openapi-generator/src/main/resources/php/libraries/psr-18/ApiException.mustache
+++ b/modules/openapi-generator/src/main/resources/php/libraries/psr-18/ApiException.mustache
@@ -44,7 +44,7 @@ class ApiException extends RequestException
     /**
      * The HTTP header of the server response.
      *
-     * @var string[]|null
+     * @var string[][]|null
      */
     protected $responseHeaders;
 
@@ -72,7 +72,7 @@ class ApiException extends RequestException
     /**
      * Gets the HTTP response header
      *
-     * @return string[]|null HTTP response header
+     * @return string[][]|null HTTP response header
      */
     public function getResponseHeaders()
     {
diff --git a/samples/client/echo_api/php-nextgen/src/ApiException.php b/samples/client/echo_api/php-nextgen/src/ApiException.php
index 7ff847f700f..fa1d216dbd9 100644
--- a/samples/client/echo_api/php-nextgen/src/ApiException.php
+++ b/samples/client/echo_api/php-nextgen/src/ApiException.php
@@ -49,7 +49,7 @@ class ApiException extends Exception
     /**
      * The HTTP header of the server response.
      *
-     * @var string[]|null
+     * @var string[][]|null
      */
     protected ?array $responseHeaders;
 
@@ -65,10 +65,10 @@ class ApiException extends Exception
      *
      * @param string                $message         Error message
      * @param int                   $code            HTTP status code
-     * @param string[]|null         $responseHeaders HTTP response header
-     * @param mixed $responseBody    HTTP decoded body of the server response either as stdClass or string
+     * @param string[][]|null       $responseHeaders HTTP response header
+     * @param stdClass|string|null  $responseBody    HTTP decoded body of the server response either as stdClass or string
      */
-    public function __construct(string $message = "", int $code = 0, ?array $responseHeaders = [], mixed $responseBody = null)
+    public function __construct(string $message = "", int $code = 0, ?array $responseHeaders = [], stdClass|string|null $responseBody = null)
     {
         parent::__construct($message, $code);
         $this->responseHeaders = $responseHeaders;
@@ -78,7 +78,7 @@ class ApiException extends Exception
     /**
      * Gets the HTTP response header
      *
-     * @return string[]|null HTTP response header
+     * @return string[][]|null HTTP response header
      */
     public function getResponseHeaders(): ?array
     {
diff --git a/samples/client/petstore/php-nextgen/OpenAPIClient-php/lib/ApiException.php b/samples/client/petstore/php-nextgen/OpenAPIClient-php/lib/ApiException.php
index 875e0fb422b..bffc807b9a2 100644
--- a/samples/client/petstore/php-nextgen/OpenAPIClient-php/lib/ApiException.php
+++ b/samples/client/petstore/php-nextgen/OpenAPIClient-php/lib/ApiException.php
@@ -49,7 +49,7 @@ class ApiException extends Exception
     /**
      * The HTTP header of the server response.
      *
-     * @var string[]|null
+     * @var string[][]|null
      */
     protected $responseHeaders;
 
@@ -65,7 +65,7 @@ class ApiException extends Exception
      *
      * @param string                $message         Error message
      * @param int                   $code            HTTP status code
-     * @param string[]|null         $responseHeaders HTTP response header
+     * @param string[][]|null       $responseHeaders HTTP response headerr
      * @param \stdClass|string|null $responseBody    HTTP decoded body of the server response either as \stdClass or string
      */
     public function __construct($message = "", $code = 0, $responseHeaders = [], $responseBody = null)
diff --git a/samples/client/petstore/php-nextgen/OpenAPIClient-php/src/ApiException.php b/samples/client/petstore/php-nextgen/OpenAPIClient-php/src/ApiException.php
index aafd4547e71..abae8cf44ac 100644
--- a/samples/client/petstore/php-nextgen/OpenAPIClient-php/src/ApiException.php
+++ b/samples/client/petstore/php-nextgen/OpenAPIClient-php/src/ApiException.php
@@ -48,7 +48,7 @@ class ApiException extends Exception
     /**
      * The HTTP header of the server response.
      *
-     * @var string[]|null
+     * @var string[][]|null
      */
     protected ?array $responseHeaders;
 
@@ -64,10 +64,10 @@ class ApiException extends Exception
      *
      * @param string                $message         Error message
      * @param int                   $code            HTTP status code
-     * @param string[]|null         $responseHeaders HTTP response header
-     * @param mixed $responseBody    HTTP decoded body of the server response either as stdClass or string
+     * @param string[][]|null       $responseHeaders HTTP response header
+     * @param stdClass|string|null  $responseBody    HTTP decoded body of the server response either as stdClass or string
      */
-    public function __construct(string $message = "", int $code = 0, ?array $responseHeaders = [], mixed $responseBody = null)
+    public function __construct(string $message = "", int $code = 0, ?array $responseHeaders = [], stdClass|string|null $responseBody = null)
     {
         parent::__construct($message, $code);
         $this->responseHeaders = $responseHeaders;
@@ -77,7 +77,7 @@ class ApiException extends Exception
     /**
      * Gets the HTTP response header
      *
-     * @return string[]|null HTTP response header
+     * @return string[][]|null HTTP response header
      */
     public function getResponseHeaders(): ?array
     {
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/ApiException.php b/samples/client/petstore/php/OpenAPIClient-php/lib/ApiException.php
index ab9bde48483..23af1e3f501 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/ApiException.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/ApiException.php
@@ -49,7 +49,7 @@ class ApiException extends Exception
     /**
      * The HTTP header of the server response.
      *
-     * @var string[]|null
+     * @var string[][]|null
      */
     protected $responseHeaders;
 
@@ -65,7 +65,7 @@ class ApiException extends Exception
      *
      * @param string                $message         Error message
      * @param int                   $code            HTTP status code
-     * @param string[]|null         $responseHeaders HTTP response header
+     * @param string[][]|null       $responseHeaders HTTP response header
      * @param \stdClass|string|null $responseBody    HTTP decoded body of the server response either as \stdClass or string
      */
     public function __construct($message = "", $code = 0, $responseHeaders = [], $responseBody = null)
@@ -78,7 +78,7 @@ class ApiException extends Exception
     /**
      * Gets the HTTP response header
      *
-     * @return string[]|null HTTP response header
+     * @return string[][]|null HTTP response header
      */
     public function getResponseHeaders()
     {
diff --git a/samples/client/petstore/php/psr-18/lib/ApiException.php b/samples/client/petstore/php/psr-18/lib/ApiException.php
index 9fb8a86ad3b..43644da9222 100644
--- a/samples/client/petstore/php/psr-18/lib/ApiException.php
+++ b/samples/client/petstore/php/psr-18/lib/ApiException.php
@@ -53,7 +53,7 @@ class ApiException extends RequestException
     /**
      * The HTTP header of the server response.
      *
-     * @var string[]|null
+     * @var string[][]|null
      */
     protected $responseHeaders;
 
@@ -81,7 +81,7 @@ class ApiException extends RequestException
     /**
      * Gets the HTTP response header
      *
-     * @return string[]|null HTTP response header
+     * @return string[][]|null HTTP response header
      */
     public function getResponseHeaders()
     {