diff --git a/CODING-CHALLENGE-8.md b/CODING-CHALLENGE-8.md
new file mode 100644
index 0000000..1e0c963
--- /dev/null
+++ b/CODING-CHALLENGE-8.md
@@ -0,0 +1,13 @@
+# 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 23b8d21..cbf94a0 100644
--- a/composer.json
+++ b/composer.json
@@ -22,6 +22,7 @@
         "symfony/property-info": "6.3.*",
         "symfony/runtime": "6.3.*",
         "symfony/serializer": "6.3.*",
+        "symfony/validator": "6.3.*",
         "symfony/yaml": "6.3.*",
         "webmozart/assert": "^1.11",
         "willdurand/negotiation": "^3.1"
diff --git a/composer.lock b/composer.lock
index e5832d7..d232182 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": "5596bf499dc7ce184640fa9df83b1cb1",
+    "content-hash": "fab137f8283c2f0c56444153bddecb62",
     "packages": [
         {
             "name": "brick/math",
@@ -4459,6 +4459,180 @@
             ],
             "time": "2023-07-05T08:41:27+00:00"
         },
+        {
+            "name": "symfony/translation-contracts",
+            "version": "v3.3.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/translation-contracts.git",
+                "reference": "02c24deb352fb0d79db5486c0c79905a85e37e86"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/translation-contracts/zipball/02c24deb352fb0d79db5486c0c79905a85e37e86",
+                "reference": "02c24deb352fb0d79db5486c0c79905a85e37e86",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=8.1"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-main": "3.4-dev"
+                },
+                "thanks": {
+                    "name": "symfony/contracts",
+                    "url": "https://github.com/symfony/contracts"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Contracts\\Translation\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Test/"
+                ]
+            },
+            "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/v3.3.0"
+            },
+            "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": "2023-05-30T17:17:10+00:00"
+        },
+        {
+            "name": "symfony/validator",
+            "version": "v6.3.4",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/validator.git",
+                "reference": "0c8435154920b9bbe93bece675234c244cadf73b"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/validator/zipball/0c8435154920b9bbe93bece675234c244cadf73b",
+                "reference": "0c8435154920b9bbe93bece675234c244cadf73b",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=8.1",
+                "symfony/deprecation-contracts": "^2.5|^3",
+                "symfony/polyfill-ctype": "~1.8",
+                "symfony/polyfill-mbstring": "~1.0",
+                "symfony/polyfill-php83": "^1.27",
+                "symfony/translation-contracts": "^2.5|^3"
+            },
+            "conflict": {
+                "doctrine/annotations": "<1.13",
+                "doctrine/lexer": "<1.1",
+                "symfony/dependency-injection": "<5.4",
+                "symfony/expression-language": "<5.4",
+                "symfony/http-kernel": "<5.4",
+                "symfony/intl": "<5.4",
+                "symfony/property-info": "<5.4",
+                "symfony/translation": "<5.4",
+                "symfony/yaml": "<5.4"
+            },
+            "require-dev": {
+                "doctrine/annotations": "^1.13|^2",
+                "egulias/email-validator": "^2.1.10|^3|^4",
+                "symfony/cache": "^5.4|^6.0",
+                "symfony/config": "^5.4|^6.0",
+                "symfony/console": "^5.4|^6.0",
+                "symfony/dependency-injection": "^5.4|^6.0",
+                "symfony/expression-language": "^5.4|^6.0",
+                "symfony/finder": "^5.4|^6.0",
+                "symfony/http-client": "^5.4|^6.0",
+                "symfony/http-foundation": "^5.4|^6.0",
+                "symfony/http-kernel": "^5.4|^6.0",
+                "symfony/intl": "^5.4|^6.0",
+                "symfony/mime": "^5.4|^6.0",
+                "symfony/property-access": "^5.4|^6.0",
+                "symfony/property-info": "^5.4|^6.0",
+                "symfony/translation": "^5.4|^6.0",
+                "symfony/yaml": "^5.4|^6.0"
+            },
+            "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/v6.3.4"
+            },
+            "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": "2023-08-17T15:49:05+00:00"
+        },
         {
             "name": "symfony/var-dumper",
             "version": "v6.3.4",
diff --git a/config/packages/validator.yaml b/config/packages/validator.yaml
new file mode 100644
index 0000000..0201281
--- /dev/null
+++ b/config/packages/validator.yaml
@@ -0,0 +1,13 @@
+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\: []
+
+when@test:
+    framework:
+        validation:
+            not_compromised_password: false
diff --git a/config/services.yaml b/config/services.yaml
index cdad506..334535c 100644
--- a/config/services.yaml
+++ b/config/services.yaml
@@ -26,3 +26,11 @@ services:
 
     # add more service definitions when explicit configuration is needed
     # please note that last definitions always *replace* previous ones
+
+
+
+when@test:
+    services:
+        Psr\Log\NullLogger: ~
+        # Disable logger to avoid showing errors during tests
+        logger: '@Psr\Log\NullLogger'
\ No newline at end of file
diff --git a/src/ArgumentValueResolver/CreateAttendeeModelResolver.php b/src/ArgumentValueResolver/CreateAttendeeModelResolver.php
index d99a1bf..ac35296 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 readonly SerializerInterface $serializer,
+        private readonly ValidatorInterface $validator
     ) {
     }
 
@@ -29,10 +32,23 @@ public function resolve(Request $request, ArgumentMetadata $argument): iterable
     {
         // it returns an iterable, because the controller method argument could be variadic
 
-        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 8f033af..4aa7197 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 readonly SerializerInterface $serializer,
+        private readonly ValidatorInterface $validator
     ) {
     }
 
@@ -27,10 +30,23 @@ public function supports(Request $request, ArgumentMetadata $argument): bool
      */
     public function resolve(Request $request, ArgumentMetadata $argument): iterable
     {
-        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 UnprocessableEntityHttpException 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 b1e4a3d..204fd77 100644
--- a/symfony.lock
+++ b/symfony.lock
@@ -160,6 +160,18 @@
             "config/routes.yaml"
         ]
     },
+    "symfony/validator": {
+        "version": "6.3",
+        "recipe": {
+            "repo": "github.com/symfony/recipes",
+            "branch": "main",
+            "version": "5.3",
+            "ref": "c32cfd98f714894c4f128bb99aa2530c1227603c"
+        },
+        "files": [
+            "config/packages/validator.yaml"
+        ]
+    },
     "theofidry/alice-data-fixtures": {
         "version": "1.6",
         "recipe": {
diff --git a/tests/Controller/Attendee/CreateControllerTest.php b/tests/Controller/Attendee/CreateControllerTest.php
index 70509e6..0618017 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 static 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..c2fe9b3 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 static function provideUnprocessableAttendeeData(): \Generator
+    {
+        yield 'no data' => [''];
+        yield 'wrong email' => ['{"email": "paulpaulsende"}'];
+    }
 }