diff --git a/modules/openapi-generator/src/main/resources/php-symfony/api_input_validation.mustache b/modules/openapi-generator/src/main/resources/php-symfony/api_input_validation.mustache
index 299b64cd764..3cda7622c71 100644
--- a/modules/openapi-generator/src/main/resources/php-symfony/api_input_validation.mustache
+++ b/modules/openapi-generator/src/main/resources/php-symfony/api_input_validation.mustache
@@ -30,7 +30,7 @@
         $asserts[] = new Assert\Date();
     {{/isDate}}
     {{#isDateTime}}
-        $asserts[] = new Assert\DateTime();
+        $asserts[] = new Assert\Type("DateTime");
     {{/isDateTime}}
     {{^isDate}}
     {{^isDateTime}}
diff --git a/modules/openapi-generator/src/main/resources/php-symfony/serialization/JmsSerializer.mustache b/modules/openapi-generator/src/main/resources/php-symfony/serialization/JmsSerializer.mustache
index 0cd5d36ca5c..444eef6760e 100644
--- a/modules/openapi-generator/src/main/resources/php-symfony/serialization/JmsSerializer.mustache
+++ b/modules/openapi-generator/src/main/resources/php-symfony/serialization/JmsSerializer.mustache
@@ -95,7 +95,7 @@ class JmsSerializer implements SerializerInterface
                 break;
             case 'DateTime':
             case '\DateTime':
-                return new DateTime($data);
+                return is_null($data) ? null :new DateTime($data);
             default:
                 throw new RuntimeException(sprintf("Type %s is unsupported", $type));
         }
diff --git a/samples/server/petstore/php-symfony/SymfonyBundle-php/Service/JmsSerializer.php b/samples/server/petstore/php-symfony/SymfonyBundle-php/Service/JmsSerializer.php
index 2beafc6fa2d..379e7faf32a 100644
--- a/samples/server/petstore/php-symfony/SymfonyBundle-php/Service/JmsSerializer.php
+++ b/samples/server/petstore/php-symfony/SymfonyBundle-php/Service/JmsSerializer.php
@@ -95,7 +95,7 @@ class JmsSerializer implements SerializerInterface
                 break;
             case 'DateTime':
             case '\DateTime':
-                return new DateTime($data);
+                return is_null($data) ? null :new DateTime($data);
             default:
                 throw new RuntimeException(sprintf("Type %s is unsupported", $type));
         }