diff --git a/CODING-CHALLENGE-8.md b/CODING-CHALLENGE-8.md
new file mode 100644
index 0000000..3a118f6
--- /dev/null
+++ b/CODING-CHALLENGE-8.md
@@ -0,0 +1,14 @@
+# RESTful Webservices in Symfony
+
+## Coding Challenge 8 - Error Handling
+
+### Tasks
+
+- centralize the error handling
+
+### Solution
+
+- throw a `ValidationFailedException` on validation errors
+- introduce an `ExceptionListener` to catch the `ValidationFailedException`
+- in the `ExceptionListener` create an error representation of the caught exception
+  and fill the response content with it
diff --git a/composer.json b/composer.json
index 4363406..3d9f1dd 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
     "type": "project",
     "license": "proprietary",
-    "minimum-stability": "dev",
+    "minimum-stability": "stable",
     "prefer-stable": true,
     "require": {
         "php": ">=8",
@@ -26,6 +26,8 @@
         "symfony/proxy-manager-bridge": "5.4.*",
         "symfony/runtime": "5.4.*",
         "symfony/serializer": "5.4.*",
+        "symfony/string": "5.4.*",
+        "symfony/validator": "5.4.*",
         "symfony/yaml": "5.4.*",
         "webmozart/assert": "^1.10",
         "willdurand/negotiation": "^3.0"
diff --git a/composer.lock b/composer.lock
index b547555..c4c4cba 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "d66fc5de0e131e7972b58a13ac74bd11",
+    "content-hash": "39a815772e16e8c23ba4c5f5f7c53fa0",
     "packages": [
         {
             "name": "brick/math",
@@ -1957,30 +1957,30 @@
         },
         {
             "name": "psr/log",
-            "version": "2.0.0",
+            "version": "1.1.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/php-fig/log.git",
-                "reference": "ef29f6d262798707a9edd554e2b82517ef3a9376"
+                "reference": "d49695b909c3b7628b6289db5479a1c204601f11"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/php-fig/log/zipball/ef29f6d262798707a9edd554e2b82517ef3a9376",
-                "reference": "ef29f6d262798707a9edd554e2b82517ef3a9376",
+                "url": "https://api.github.com/repos/php-fig/log/zipball/d49695b909c3b7628b6289db5479a1c204601f11",
+                "reference": "d49695b909c3b7628b6289db5479a1c204601f11",
                 "shasum": ""
             },
             "require": {
-                "php": ">=8.0.0"
+                "php": ">=5.3.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.0.x-dev"
+                    "dev-master": "1.1.x-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
-                    "Psr\\Log\\": "src"
+                    "Psr\\Log\\": "Psr/Log/"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -2001,9 +2001,9 @@
                 "psr-3"
             ],
             "support": {
-                "source": "https://github.com/php-fig/log/tree/2.0.0"
+                "source": "https://github.com/php-fig/log/tree/1.1.4"
             },
-            "time": "2021-07-14T16:41:46+00:00"
+            "time": "2021-05-03T11:20:27+00:00"
         },
         {
             "name": "ramsey/collection",
@@ -5014,6 +5014,196 @@
             ],
             "time": "2021-11-24T10:02:00+00:00"
         },
+        {
+            "name": "symfony/translation-contracts",
+            "version": "v2.5.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/translation-contracts.git",
+                "reference": "d28150f0f44ce854e942b671fc2620a98aae1b1e"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/translation-contracts/zipball/d28150f0f44ce854e942b671fc2620a98aae1b1e",
+                "reference": "d28150f0f44ce854e942b671fc2620a98aae1b1e",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=7.2.5"
+            },
+            "suggest": {
+                "symfony/translation-implementation": ""
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-main": "2.5-dev"
+                },
+                "thanks": {
+                    "name": "symfony/contracts",
+                    "url": "https://github.com/symfony/contracts"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Contracts\\Translation\\": ""
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nicolas Grekas",
+                    "email": "p@tchwork.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Generic abstractions related to translation",
+            "homepage": "https://symfony.com",
+            "keywords": [
+                "abstractions",
+                "contracts",
+                "decoupling",
+                "interfaces",
+                "interoperability",
+                "standards"
+            ],
+            "support": {
+                "source": "https://github.com/symfony/translation-contracts/tree/v2.5.0"
+            },
+            "funding": [
+                {
+                    "url": "https://symfony.com/sponsor",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://github.com/fabpot",
+                    "type": "github"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/symfony/symfony",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2021-08-17T14:20:01+00:00"
+        },
+        {
+            "name": "symfony/validator",
+            "version": "v5.4.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/validator.git",
+                "reference": "68db3401621f75b285cf54ac83e3b89066e08f8d"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/validator/zipball/68db3401621f75b285cf54ac83e3b89066e08f8d",
+                "reference": "68db3401621f75b285cf54ac83e3b89066e08f8d",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=7.2.5",
+                "symfony/deprecation-contracts": "^2.1|^3",
+                "symfony/polyfill-ctype": "~1.8",
+                "symfony/polyfill-mbstring": "~1.0",
+                "symfony/polyfill-php73": "~1.0",
+                "symfony/polyfill-php80": "^1.16",
+                "symfony/translation-contracts": "^1.1|^2|^3"
+            },
+            "conflict": {
+                "doctrine/annotations": "<1.13",
+                "doctrine/cache": "<1.11",
+                "doctrine/lexer": "<1.0.2",
+                "phpunit/phpunit": "<5.4.3",
+                "symfony/dependency-injection": "<4.4",
+                "symfony/expression-language": "<5.1",
+                "symfony/http-kernel": "<4.4",
+                "symfony/intl": "<4.4",
+                "symfony/property-info": "<5.3",
+                "symfony/translation": "<4.4",
+                "symfony/yaml": "<4.4"
+            },
+            "require-dev": {
+                "doctrine/annotations": "^1.13",
+                "doctrine/cache": "^1.11|^2.0",
+                "egulias/email-validator": "^2.1.10|^3",
+                "symfony/cache": "^4.4|^5.0|^6.0",
+                "symfony/config": "^4.4|^5.0|^6.0",
+                "symfony/console": "^4.4|^5.0|^6.0",
+                "symfony/dependency-injection": "^4.4|^5.0|^6.0",
+                "symfony/expression-language": "^5.1|^6.0",
+                "symfony/finder": "^4.4|^5.0|^6.0",
+                "symfony/http-client": "^4.4|^5.0|^6.0",
+                "symfony/http-foundation": "^4.4|^5.0|^6.0",
+                "symfony/http-kernel": "^4.4|^5.0|^6.0",
+                "symfony/intl": "^4.4|^5.0|^6.0",
+                "symfony/mime": "^4.4|^5.0|^6.0",
+                "symfony/property-access": "^4.4|^5.0|^6.0",
+                "symfony/property-info": "^5.3|^6.0",
+                "symfony/translation": "^4.4|^5.0|^6.0",
+                "symfony/yaml": "^4.4|^5.0|^6.0"
+            },
+            "suggest": {
+                "egulias/email-validator": "Strict (RFC compliant) email validation",
+                "psr/cache-implementation": "For using the mapping cache.",
+                "symfony/config": "",
+                "symfony/expression-language": "For using the Expression validator and the ExpressionLanguageSyntax constraints",
+                "symfony/http-foundation": "",
+                "symfony/intl": "",
+                "symfony/property-access": "For accessing properties within comparison constraints",
+                "symfony/property-info": "To automatically add NotNull and Type constraints",
+                "symfony/translation": "For translating validation errors.",
+                "symfony/yaml": ""
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Component\\Validator\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Provides tools to validate values",
+            "homepage": "https://symfony.com",
+            "support": {
+                "source": "https://github.com/symfony/validator/tree/v5.4.0"
+            },
+            "funding": [
+                {
+                    "url": "https://symfony.com/sponsor",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://github.com/fabpot",
+                    "type": "github"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/symfony/symfony",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2021-11-29T15:30:56+00:00"
+        },
         {
             "name": "symfony/var-dumper",
             "version": "v5.4.0",
@@ -5733,16 +5923,16 @@
         },
         {
             "name": "hautelook/alice-bundle",
-            "version": "dev-master",
+            "version": "2.9.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/theofidry/AliceBundle.git",
-                "reference": "ada5be333c79c494330d91d790b1f6674350c3f6"
+                "reference": "17c5199b2a6efbc1383b0afe1cddfa3c176b7b6f"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/theofidry/AliceBundle/zipball/ada5be333c79c494330d91d790b1f6674350c3f6",
-                "reference": "ada5be333c79c494330d91d790b1f6674350c3f6",
+                "url": "https://api.github.com/repos/theofidry/AliceBundle/zipball/17c5199b2a6efbc1383b0afe1cddfa3c176b7b6f",
+                "reference": "17c5199b2a6efbc1383b0afe1cddfa3c176b7b6f",
                 "shasum": ""
             },
             "require": {
@@ -5751,7 +5941,7 @@
                 "doctrine/orm": "^2.5.11",
                 "doctrine/persistence": "^1.3.4 || ^2.0",
                 "php": "^7.3 || ^8.0",
-                "psr/log": "^1.0 || ^2.0 || ^3.0",
+                "psr/log": "^1.0",
                 "symfony/finder": "^3.4 || ^4.0 || ^5.0",
                 "symfony/framework-bundle": "^3.4.24 || ^4.0 || ^5.0",
                 "theofidry/alice-data-fixtures": "^1.4"
@@ -5761,7 +5951,6 @@
                 "phpunit/phpunit": "^8.5",
                 "symfony/phpunit-bridge": "^5.1"
             },
-            "default-branch": true,
             "type": "symfony-bundle",
             "extra": {
                 "branch-alias": {
@@ -5799,8 +5988,7 @@
                 "symfony"
             ],
             "support": {
-                "issues": "https://github.com/theofidry/AliceBundle/issues",
-                "source": "https://github.com/theofidry/AliceBundle/tree/master"
+                "source": "https://github.com/theofidry/AliceBundle/tree/2.9.0"
             },
             "funding": [
                 {
@@ -5808,7 +5996,7 @@
                     "type": "github"
                 }
             ],
-            "time": "2021-11-04T08:18:45+00:00"
+            "time": "2021-02-23T08:45:57+00:00"
         },
         {
             "name": "myclabs/deep-copy",
@@ -8125,29 +8313,28 @@
         },
         {
             "name": "theofidry/alice-data-fixtures",
-            "version": "dev-master",
+            "version": "1.4.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/theofidry/AliceDataFixtures.git",
-                "reference": "9e94af9bb1bd47b0e6069d3760d002f182e5763f"
+                "reference": "bcfdf64bc940eb4a7b40b46d9ca5251e5692cc11"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/theofidry/AliceDataFixtures/zipball/9e94af9bb1bd47b0e6069d3760d002f182e5763f",
-                "reference": "9e94af9bb1bd47b0e6069d3760d002f182e5763f",
+                "url": "https://api.github.com/repos/theofidry/AliceDataFixtures/zipball/bcfdf64bc940eb4a7b40b46d9ca5251e5692cc11",
+                "reference": "bcfdf64bc940eb4a7b40b46d9ca5251e5692cc11",
                 "shasum": ""
             },
             "require": {
                 "nelmio/alice": "^3.5",
-                "php": "^7.4 || ^8.0",
-                "psr/log": "^1 || ^2 || ^3"
+                "php": "^7.3 | ^8.0",
+                "psr/log": "^1.0"
             },
             "conflict": {
                 "doctrine/orm": "<2.6.3",
-                "doctrine/persistence": "<1.4",
                 "illuminate/database": "<5.5",
                 "ocramius/proxy-manager": "<2.1",
-                "symfony/framework-bundle": "<4.4 || >5.0,<5.3",
+                "symfony/framework-bundle": "<3.4",
                 "zendframework/zend-code": "<3.3.1"
             },
             "require-dev": {
@@ -8169,7 +8356,6 @@
                 "jackalope/jackalope-doctrine-dbal": "To use Doctrine with the PHPCR flavour",
                 "ocramius/proxy-manager": "To avoid database connection on kernel boot"
             },
-            "default-branch": true,
             "type": "library",
             "extra": {
                 "bamarni-bin": {
@@ -8206,7 +8392,7 @@
             ],
             "support": {
                 "issues": "https://github.com/theofidry/AliceDataFixtures/issues",
-                "source": "https://github.com/theofidry/AliceDataFixtures/tree/master"
+                "source": "https://github.com/theofidry/AliceDataFixtures/tree/1.4.0"
             },
             "funding": [
                 {
@@ -8214,7 +8400,7 @@
                     "type": "github"
                 }
             ],
-            "time": "2021-10-17T09:13:11+00:00"
+            "time": "2021-01-25T10:07:17+00:00"
         },
         {
             "name": "theseer/tokenizer",
@@ -8268,7 +8454,7 @@
         }
     ],
     "aliases": [],
-    "minimum-stability": "dev",
+    "minimum-stability": "stable",
     "stability-flags": [],
     "prefer-stable": true,
     "prefer-lowest": false,
diff --git a/config/packages/test/validator.yaml b/config/packages/test/validator.yaml
new file mode 100644
index 0000000..1e5ab78
--- /dev/null
+++ b/config/packages/test/validator.yaml
@@ -0,0 +1,3 @@
+framework:
+    validation:
+        not_compromised_password: false
diff --git a/config/packages/validator.yaml b/config/packages/validator.yaml
new file mode 100644
index 0000000..350786a
--- /dev/null
+++ b/config/packages/validator.yaml
@@ -0,0 +1,8 @@
+framework:
+    validation:
+        email_validation_mode: html5
+
+        # Enables validator auto-mapping support.
+        # For instance, basic validation constraints will be inferred from Doctrine's metadata.
+        #auto_mapping:
+        #    App\Entity\: []
diff --git a/src/ArgumentValueResolver/CreateAttendeeModelResolver.php b/src/ArgumentValueResolver/CreateAttendeeModelResolver.php
index be4493f..7eec489 100644
--- a/src/ArgumentValueResolver/CreateAttendeeModelResolver.php
+++ b/src/ArgumentValueResolver/CreateAttendeeModelResolver.php
@@ -8,12 +8,15 @@
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Controller\ArgumentValueResolverInterface;
 use Symfony\Component\HttpKernel\ControllerMetadata\ArgumentMetadata;
+use Symfony\Component\HttpKernel\Exception\UnprocessableEntityHttpException;
 use Symfony\Component\Serializer\SerializerInterface;
+use Symfony\Component\Validator\Validator\ValidatorInterface;
 
 final class CreateAttendeeModelResolver implements ArgumentValueResolverInterface
 {
     public function __construct(
         private SerializerInterface $serializer,
+        private ValidatorInterface $validator,
     ) {
     }
 
@@ -27,10 +30,23 @@ public function supports(Request $request, ArgumentMetadata $argument): bool
      */
     public function resolve(Request $request, ArgumentMetadata $argument)
     {
-        yield $this->serializer->deserialize(
-            $request->getContent(),
-            CreateAttendeeModel::class,
-            $request->getRequestFormat(),
-        );
+        try {
+            $model = $this->serializer->deserialize(
+                $request->getContent(),
+                CreateAttendeeModel::class,
+                $request->getRequestFormat(),
+            );
+        } catch (\Exception $exception) {
+            throw new UnprocessableEntityHttpException();
+        }
+
+        $validationErrors = $this->validator->validate($model);
+
+        if (\count($validationErrors) > 0) {
+            // throw a UnprocessableEntityHttpException for now, we will introduce proper ApiExceptions later
+            throw new UnprocessableEntityHttpException();
+        }
+
+        yield $model;
     }
 }
diff --git a/src/ArgumentValueResolver/UpdateAttendeeModelResolver.php b/src/ArgumentValueResolver/UpdateAttendeeModelResolver.php
index 6182dea..3ba6ace 100644
--- a/src/ArgumentValueResolver/UpdateAttendeeModelResolver.php
+++ b/src/ArgumentValueResolver/UpdateAttendeeModelResolver.php
@@ -8,12 +8,15 @@
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Controller\ArgumentValueResolverInterface;
 use Symfony\Component\HttpKernel\ControllerMetadata\ArgumentMetadata;
+use Symfony\Component\HttpKernel\Exception\UnprocessableEntityHttpException;
 use Symfony\Component\Serializer\SerializerInterface;
+use Symfony\Component\Validator\Validator\ValidatorInterface;
 
 final class UpdateAttendeeModelResolver implements ArgumentValueResolverInterface
 {
     public function __construct(
         private SerializerInterface $serializer,
+        private ValidatorInterface $validator,
     ) {
     }
 
@@ -27,10 +30,23 @@ public function supports(Request $request, ArgumentMetadata $argument): bool
      */
     public function resolve(Request $request, ArgumentMetadata $argument)
     {
-        yield $this->serializer->deserialize(
-            $request->getContent(),
-            UpdateAttendeeModel::class,
-            $request->getRequestFormat(),
-        );
+        try {
+            $model = $this->serializer->deserialize(
+                $request->getContent(),
+                UpdateAttendeeModel::class,
+                $request->getRequestFormat(),
+            );
+        } catch (\Exception $exception) {
+            throw new UnprocessableEntityHttpException();
+        }
+
+        $validationErrors = $this->validator->validate($model);
+
+        if (\count($validationErrors) > 0) {
+            // throw a BadRequestHttpException for now, we will introduce proper ApiExceptions later
+            throw new UnprocessableEntityHttpException();
+        }
+
+        yield $model;
     }
 }
diff --git a/src/Domain/Model/CreateAttendeeModel.php b/src/Domain/Model/CreateAttendeeModel.php
index 277501b..691675c 100644
--- a/src/Domain/Model/CreateAttendeeModel.php
+++ b/src/Domain/Model/CreateAttendeeModel.php
@@ -4,9 +4,18 @@
 
 namespace App\Domain\Model;
 
+use Symfony\Component\Validator\Constraints\Email;
+use Symfony\Component\Validator\Constraints\NotBlank;
+
 final class CreateAttendeeModel
 {
+    #[NotBlank]
     public string $firstname;
+
+    #[NotBlank]
     public string $lastname;
+
+    #[NotBlank]
+    #[Email]
     public string $email;
 }
diff --git a/src/Domain/Model/UpdateAttendeeModel.php b/src/Domain/Model/UpdateAttendeeModel.php
index 98a6d82..cf2b7f1 100644
--- a/src/Domain/Model/UpdateAttendeeModel.php
+++ b/src/Domain/Model/UpdateAttendeeModel.php
@@ -4,9 +4,18 @@
 
 namespace App\Domain\Model;
 
+use Symfony\Component\Validator\Constraints\Email;
+use Symfony\Component\Validator\Constraints\NotBlank;
+
 final class UpdateAttendeeModel
 {
+    #[NotBlank(allowNull: true)]
     public ?string $firstname = null;
+
+    #[NotBlank(allowNull: true)]
     public ?string $lastname = null;
+
+    #[NotBlank(allowNull: true)]
+    #[Email]
     public ?string $email = null;
 }
diff --git a/symfony.lock b/symfony.lock
index 5f95e5b..c7bafd9 100644
--- a/symfony.lock
+++ b/symfony.lock
@@ -461,6 +461,22 @@
     "symfony/string": {
         "version": "v5.4.0-RC1"
     },
+    "symfony/translation-contracts": {
+        "version": "v3.0.0"
+    },
+    "symfony/validator": {
+        "version": "5.4",
+        "recipe": {
+            "repo": "github.com/symfony/recipes",
+            "branch": "master",
+            "version": "4.3",
+            "ref": "3eb8df139ec05414489d55b97603c5f6ca0c44cb"
+        },
+        "files": [
+            "config/packages/test/validator.yaml",
+            "config/packages/validator.yaml"
+        ]
+    },
     "symfony/var-dumper": {
         "version": "v5.4.0-RC1"
     },
diff --git a/tests/Controller/Attendee/CreateControllerTest.php b/tests/Controller/Attendee/CreateControllerTest.php
index 70509e6..9f09894 100644
--- a/tests/Controller/Attendee/CreateControllerTest.php
+++ b/tests/Controller/Attendee/CreateControllerTest.php
@@ -38,4 +38,28 @@ public function test_it_should_create_an_attendee(): void
         static::assertSame('Paulsen', $expectedAttendee->getLastname());
         static::assertSame('paul@paulsen.de', $expectedAttendee->getEmail());
     }
+
+    /**
+     * @dataProvider provideUnprocessableAttendeeData
+     */
+    public function test_it_should_throw_an_UnprocessableEntityHttpException(string $requestBody): void
+    {
+        $this->browser->request('POST', '/attendees', [], [], [], $requestBody);
+
+        static::assertResponseStatusCodeSame(422);
+        static::assertStringContainsString(
+            'UnprocessableEntityHttpException',
+            $this->browser->getResponse()->getContent()
+        );
+    }
+
+    public function provideUnprocessableAttendeeData(): \Generator
+    {
+        yield 'no data' => [''];
+        yield 'empty data' => ['{}'];
+        yield 'missing firstname' => ['{"lastname": "Paulsen", "email": "paul@paulsen.de"}'];
+        yield 'missing lastname' => ['{"firstname": "Paul", "email": "paul@paulsen.de"}'];
+        yield 'missing email' => ['{"firstname": "Paul", "lastname": "Paulsen"}'];
+        yield 'wrong email' => ['{"firstname": "Paul", "lastname": "Paulsen", "email": "paulpaulsende"}'];
+    }
 }
diff --git a/tests/Controller/Attendee/UpdateControllerTest.php b/tests/Controller/Attendee/UpdateControllerTest.php
index 5f11654..fea8162 100644
--- a/tests/Controller/Attendee/UpdateControllerTest.php
+++ b/tests/Controller/Attendee/UpdateControllerTest.php
@@ -40,4 +40,31 @@ public function test_it_should_update_an_attendee(): void
         static::assertSame('Paulsen', $expectedAttendee->getLastname());
         static::assertSame('paul@paulsen.de', $expectedAttendee->getEmail());
     }
+
+    /**
+     * @dataProvider provideUnprocessableAttendeeData
+     */
+    public function test_it_should_throw_an_UnprocessableEntityHttpException(string $requestBody): void
+    {
+        $this->loadFixtures([
+            __DIR__.'/fixtures/update_attendee.yaml',
+        ]);
+
+        $attendeesBefore = static::getContainer()->get(AttendeeRepository::class)->findAll();
+        static::assertCount(1, $attendeesBefore);
+
+        $this->browser->request('PUT', '/attendees/b38aa3e4-f9de-4dca-aaeb-3ec36a9feb6c', [], [], [], $requestBody);
+
+        static::assertResponseStatusCodeSame(422);
+        static::assertStringContainsString(
+            'UnprocessableEntityHttpException',
+            $this->browser->getResponse()->getContent()
+        );
+    }
+
+    public function provideUnprocessableAttendeeData(): \Generator
+    {
+        yield 'no data' => [''];
+        yield 'wrong email' => ['{"email": "paulpaulsende"}'];
+    }
 }