diff --git a/Attribute/DeprecatedAlias.php b/Attribute/DeprecatedAlias.php
new file mode 100644
index 00000000..ae5a6821
--- /dev/null
+++ b/Attribute/DeprecatedAlias.php
@@ -0,0 +1,46 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Routing\Attribute;
+
+/**
+ * This class is meant to be used in {@see Route} to define an alias for a route.
+ */
+class DeprecatedAlias
+{
+    public function __construct(
+        private string $aliasName,
+        private string $package,
+        private string $version,
+        private string $message = '',
+    ) {
+    }
+
+    public function getMessage(): string
+    {
+        return $this->message;
+    }
+
+    public function getAliasName(): string
+    {
+        return $this->aliasName;
+    }
+
+    public function getPackage(): string
+    {
+        return $this->package;
+    }
+
+    public function getVersion(): string
+    {
+        return $this->version;
+    }
+}
diff --git a/Attribute/Route.php b/Attribute/Route.php
index 07abc556..003bbe64 100644
--- a/Attribute/Route.php
+++ b/Attribute/Route.php
@@ -22,23 +22,28 @@ class Route
     private array $localizedPaths = [];
     private array $methods;
     private array $schemes;
+    /**
+     * @var (string|DeprecatedAlias)[]
+     */
+    private array $aliases = [];
 
     /**
-     * @param string|array<string,string>|null $path         The route path (i.e. "/user/login")
-     * @param string|null                      $name         The route name (i.e. "app_user_login")
-     * @param array<string|\Stringable>        $requirements Requirements for the route attributes, @see https://symfony.com/doc/current/routing.html#parameters-validation
-     * @param array<string, mixed>             $options      Options for the route (i.e. ['prefix' => '/api'])
-     * @param array<string, mixed>             $defaults     Default values for the route attributes and query parameters
-     * @param string|null                      $host         The host for which this route should be active (i.e. "localhost")
-     * @param string|string[]                  $methods      The list of HTTP methods allowed by this route
-     * @param string|string[]                  $schemes      The list of schemes allowed by this route (i.e. "https")
-     * @param string|null                      $condition    An expression that must evaluate to true for the route to be matched, @see https://symfony.com/doc/current/routing.html#matching-expressions
-     * @param int|null                         $priority     The priority of the route if multiple ones are defined for the same path
-     * @param string|null                      $locale       The locale accepted by the route
-     * @param string|null                      $format       The format returned by the route (i.e. "json", "xml")
-     * @param bool|null                        $utf8         Whether the route accepts UTF-8 in its parameters
-     * @param bool|null                        $stateless    Whether the route is defined as stateless or stateful, @see https://symfony.com/doc/current/routing.html#stateless-routes
-     * @param string|null                      $env          The env in which the route is defined (i.e. "dev", "test", "prod")
+     * @param string|array<string,string>|null                  $path         The route path (i.e. "/user/login")
+     * @param string|null                                       $name         The route name (i.e. "app_user_login")
+     * @param array<string|\Stringable>                         $requirements Requirements for the route attributes, @see https://symfony.com/doc/current/routing.html#parameters-validation
+     * @param array<string, mixed>                              $options      Options for the route (i.e. ['prefix' => '/api'])
+     * @param array<string, mixed>                              $defaults     Default values for the route attributes and query parameters
+     * @param string|null                                       $host         The host for which this route should be active (i.e. "localhost")
+     * @param string|string[]                                   $methods      The list of HTTP methods allowed by this route
+     * @param string|string[]                                   $schemes      The list of schemes allowed by this route (i.e. "https")
+     * @param string|null                                       $condition    An expression that must evaluate to true for the route to be matched, @see https://symfony.com/doc/current/routing.html#matching-expressions
+     * @param int|null                                          $priority     The priority of the route if multiple ones are defined for the same path
+     * @param string|null                                       $locale       The locale accepted by the route
+     * @param string|null                                       $format       The format returned by the route (i.e. "json", "xml")
+     * @param bool|null                                         $utf8         Whether the route accepts UTF-8 in its parameters
+     * @param bool|null                                         $stateless    Whether the route is defined as stateless or stateful, @see https://symfony.com/doc/current/routing.html#stateless-routes
+     * @param string|null                                       $env          The env in which the route is defined (i.e. "dev", "test", "prod")
+     * @param string|DeprecatedAlias|(string|DeprecatedAlias)[] $alias        The list of aliases for this route
      */
     public function __construct(
         string|array|null $path = null,
@@ -56,6 +61,7 @@ public function __construct(
         ?bool $utf8 = null,
         ?bool $stateless = null,
         private ?string $env = null,
+        string|DeprecatedAlias|array $alias = [],
     ) {
         if (\is_array($path)) {
             $this->localizedPaths = $path;
@@ -64,6 +70,7 @@ public function __construct(
         }
         $this->setMethods($methods);
         $this->setSchemes($schemes);
+        $this->setAliases($alias);
 
         if (null !== $locale) {
             $this->defaults['_locale'] = $locale;
@@ -201,6 +208,22 @@ public function getEnv(): ?string
     {
         return $this->env;
     }
+
+    /**
+     * @return (string|DeprecatedAlias)[]
+     */
+    public function getAliases(): array
+    {
+        return $this->aliases;
+    }
+
+    /**
+     * @param string|DeprecatedAlias|(string|DeprecatedAlias)[] $aliases
+     */
+    public function setAliases(string|DeprecatedAlias|array $aliases): void
+    {
+        $this->aliases = \is_array($aliases) ? $aliases : [$aliases];
+    }
 }
 
 if (!class_exists(\Symfony\Component\Routing\Annotation\Route::class, false)) {
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c461405..d21e550f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,12 @@
 CHANGELOG
 =========
 
+7.3
+---
+
+ * Allow aliases and deprecations in `#[Route]` attribute
+ * Add the `Requirement::MONGODB_ID` constant to validate MongoDB ObjectIDs in hexadecimal format
+
 7.2
 ---
 
diff --git a/Loader/AttributeClassLoader.php b/Loader/AttributeClassLoader.php
index 92471af0..254582bf 100644
--- a/Loader/AttributeClassLoader.php
+++ b/Loader/AttributeClassLoader.php
@@ -14,7 +14,9 @@
 use Symfony\Component\Config\Loader\LoaderInterface;
 use Symfony\Component\Config\Loader\LoaderResolverInterface;
 use Symfony\Component\Config\Resource\FileResource;
+use Symfony\Component\Routing\Attribute\DeprecatedAlias;
 use Symfony\Component\Routing\Attribute\Route as RouteAttribute;
+use Symfony\Component\Routing\Exception\InvalidArgumentException;
 use Symfony\Component\Routing\Exception\LogicException;
 use Symfony\Component\Routing\Route;
 use Symfony\Component\Routing\RouteCollection;
@@ -107,6 +109,15 @@ public function load(mixed $class, ?string $type = null): RouteCollection
             return $collection;
         }
         $fqcnAlias = false;
+
+        if (!$class->hasMethod('__invoke')) {
+            foreach ($this->getAttributes($class) as $attr) {
+                if ($attr->getAliases()) {
+                    throw new InvalidArgumentException(\sprintf('Route aliases cannot be used on non-invokable class "%s".', $class->getName()));
+                }
+            }
+        }
+
         foreach ($class->getMethods() as $method) {
             $this->defaultRouteIndex = 0;
             $routeNamesBefore = array_keys($collection->all());
@@ -230,6 +241,19 @@ protected function addRoute(RouteCollection $collection, object $attr, array $gl
             } else {
                 $collection->add($name, $route, $priority);
             }
+            foreach ($attr->getAliases() as $aliasAttribute) {
+                if ($aliasAttribute instanceof DeprecatedAlias) {
+                    $alias = $collection->addAlias($aliasAttribute->getAliasName(), $name);
+                    $alias->setDeprecated(
+                        $aliasAttribute->getPackage(),
+                        $aliasAttribute->getVersion(),
+                        $aliasAttribute->getMessage()
+                    );
+                    continue;
+                }
+
+                $collection->addAlias($aliasAttribute, $name);
+            }
         }
     }
 
diff --git a/Loader/Psr4DirectoryLoader.php b/Loader/Psr4DirectoryLoader.php
index 738b56f4..fb48da15 100644
--- a/Loader/Psr4DirectoryLoader.php
+++ b/Loader/Psr4DirectoryLoader.php
@@ -15,6 +15,7 @@
 use Symfony\Component\Config\Loader\DirectoryAwareLoaderInterface;
 use Symfony\Component\Config\Loader\Loader;
 use Symfony\Component\Config\Resource\DirectoryResource;
+use Symfony\Component\Routing\Exception\InvalidArgumentException;
 use Symfony\Component\Routing\RouteCollection;
 
 /**
@@ -43,6 +44,10 @@ public function load(mixed $resource, ?string $type = null): ?RouteCollection
             return new RouteCollection();
         }
 
+        if (!preg_match('/^(?:[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*+\\\)++$/', trim($resource['namespace'], '\\').'\\')) {
+            throw new InvalidArgumentException(\sprintf('Namespace "%s" is not a valid PSR-4 prefix.', $resource['namespace']));
+        }
+
         return $this->loadFromDirectory($path, trim($resource['namespace'], '\\'));
     }
 
diff --git a/Requirement/Requirement.php b/Requirement/Requirement.php
index fdc0009c..6de2fbc5 100644
--- a/Requirement/Requirement.php
+++ b/Requirement/Requirement.php
@@ -20,6 +20,7 @@ enum Requirement
     public const CATCH_ALL = '.+';
     public const DATE_YMD = '[0-9]{4}-(?:0[1-9]|1[012])-(?:0[1-9]|[12][0-9]|(?<!02-)3[01])'; // YYYY-MM-DD
     public const DIGITS = '[0-9]+';
+    public const MONGODB_ID = '[0-9a-f]{24}';
     public const POSITIVE_INT = '[1-9][0-9]*';
     public const UID_BASE32 = '[0-9A-HJKMNP-TV-Z]{26}';
     public const UID_BASE58 = '[1-9A-HJ-NP-Za-km-z]{22}';
diff --git a/Route.php b/Route.php
index 0364fdd0..621a4239 100644
--- a/Route.php
+++ b/Route.php
@@ -418,15 +418,15 @@ private function extractInlineDefaultsAndRequirements(string $pattern): string
 
         $mapping = $this->getDefault('_route_mapping') ?? [];
 
-        $pattern = preg_replace_callback('#\{(!?)([\w\x80-\xFF]++)(:[\w\x80-\xFF]++)?(<.*?>)?(\?[^\}]*+)?\}#', function ($m) use (&$mapping) {
-            if (isset($m[5][0])) {
-                $this->setDefault($m[2], '?' !== $m[5] ? substr($m[5], 1) : null);
+        $pattern = preg_replace_callback('#\{(!?)([\w\x80-\xFF]++)(:([\w\x80-\xFF]++)(\.[\w\x80-\xFF]++)?)?(<.*?>)?(\?[^\}]*+)?\}#', function ($m) use (&$mapping) {
+            if (isset($m[7][0])) {
+                $this->setDefault($m[2], '?' !== $m[7] ? substr($m[7], 1) : null);
             }
-            if (isset($m[4][0])) {
-                $this->setRequirement($m[2], substr($m[4], 1, -1));
+            if (isset($m[6][0])) {
+                $this->setRequirement($m[2], substr($m[6], 1, -1));
             }
-            if (isset($m[3][0])) {
-                $mapping[$m[2]] = substr($m[3], 1);
+            if (isset($m[4][0])) {
+                $mapping[$m[2]] = isset($m[5][0]) ? [$m[4], substr($m[5], 1)] : $mapping[$m[2]] = [$m[4], $m[2]];
             }
 
             return '{'.$m[1].$m[2].'}';
diff --git a/Tests/Attribute/RouteTest.php b/Tests/Attribute/RouteTest.php
index 2696991c..bbaa7563 100644
--- a/Tests/Attribute/RouteTest.php
+++ b/Tests/Attribute/RouteTest.php
@@ -9,7 +9,7 @@
  * file that was distributed with this source code.
  */
 
-namespace Symfony\Component\Routing\Tests\Annotation;
+namespace Symfony\Component\Routing\Tests\Attribute;
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Routing\Attribute\Route;
@@ -40,6 +40,7 @@ public static function getValidParameters(): iterable
             ['methods', 'getMethods', ['GET', 'POST']],
             ['host', 'getHost', '{locale}.example.com'],
             ['condition', 'getCondition', 'context.getMethod() == \'GET\''],
+            ['alias', 'getAliases', ['alias', 'completely_different_name']],
         ];
     }
 }
diff --git a/Tests/Fixtures/AttributeFixtures/AliasClassController.php b/Tests/Fixtures/AttributeFixtures/AliasClassController.php
new file mode 100644
index 00000000..c7e87128
--- /dev/null
+++ b/Tests/Fixtures/AttributeFixtures/AliasClassController.php
@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures;
+
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\Routing\Attribute\Route;
+
+#[Route('/hello', alias: ['alias', 'completely_different_name'])]
+class AliasClassController
+{
+    #[Route('/world')]
+    public function actionWorld()
+    {
+    }
+
+    #[Route('/symfony')]
+    public function actionSymfony()
+    {
+    }
+}
diff --git a/Tests/Fixtures/AttributeFixtures/AliasInvokableController.php b/Tests/Fixtures/AttributeFixtures/AliasInvokableController.php
new file mode 100644
index 00000000..dac27b67
--- /dev/null
+++ b/Tests/Fixtures/AttributeFixtures/AliasInvokableController.php
@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures;
+
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\Routing\Attribute\Route;
+
+#[Route('/path', name:'invokable_path', alias: ['alias', 'completely_different_name'])]
+class AliasInvokableController
+{
+    public function __invoke()
+    {
+    }
+}
diff --git a/Tests/Fixtures/AttributeFixtures/AliasRouteController.php b/Tests/Fixtures/AttributeFixtures/AliasRouteController.php
new file mode 100644
index 00000000..0b828576
--- /dev/null
+++ b/Tests/Fixtures/AttributeFixtures/AliasRouteController.php
@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures;
+
+use Symfony\Component\Routing\Attribute\Route;
+
+class AliasRouteController
+{
+    #[Route('/path', name: 'action_with_alias', alias: ['alias', 'completely_different_name'])]
+    public function action()
+    {
+    }
+}
diff --git a/Tests/Fixtures/AttributeFixtures/DeprecatedAliasCustomMessageRouteController.php b/Tests/Fixtures/AttributeFixtures/DeprecatedAliasCustomMessageRouteController.php
new file mode 100644
index 00000000..08b1afbd
--- /dev/null
+++ b/Tests/Fixtures/AttributeFixtures/DeprecatedAliasCustomMessageRouteController.php
@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures;
+
+use Symfony\Component\Routing\Attribute\DeprecatedAlias;
+use Symfony\Component\Routing\Attribute\Route;
+
+class DeprecatedAliasCustomMessageRouteController
+{
+
+    #[Route('/path', name: 'action_with_deprecated_alias', alias: new DeprecatedAlias('my_other_alias_deprecated', 'MyBundleFixture', '1.0', message: '%alias_id% alias is deprecated.'))]
+    public function action()
+    {
+    }
+}
diff --git a/Tests/Fixtures/AttributeFixtures/DeprecatedAliasRouteController.php b/Tests/Fixtures/AttributeFixtures/DeprecatedAliasRouteController.php
new file mode 100644
index 00000000..06577cd7
--- /dev/null
+++ b/Tests/Fixtures/AttributeFixtures/DeprecatedAliasRouteController.php
@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures;
+
+use Symfony\Component\Routing\Attribute\DeprecatedAlias;
+use Symfony\Component\Routing\Attribute\Route;
+
+class DeprecatedAliasRouteController
+{
+    #[Route('/path', name: 'action_with_deprecated_alias', alias: new DeprecatedAlias('my_other_alias_deprecated', 'MyBundleFixture', '1.0'))]
+    public function action()
+    {
+    }
+}
diff --git a/Tests/Fixtures/AttributeFixtures/FooController.php b/Tests/Fixtures/AttributeFixtures/FooController.php
index adbd038a..ba822865 100644
--- a/Tests/Fixtures/AttributeFixtures/FooController.php
+++ b/Tests/Fixtures/AttributeFixtures/FooController.php
@@ -55,4 +55,9 @@ public function host()
     public function condition()
     {
     }
+
+    #[Route(alias: ['alias', 'completely_different_name'])]
+    public function alias()
+    {
+    }
 }
diff --git a/Tests/Fixtures/AttributeFixtures/MultipleDeprecatedAliasRouteController.php b/Tests/Fixtures/AttributeFixtures/MultipleDeprecatedAliasRouteController.php
new file mode 100644
index 00000000..93662d38
--- /dev/null
+++ b/Tests/Fixtures/AttributeFixtures/MultipleDeprecatedAliasRouteController.php
@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures;
+
+use Symfony\Component\Routing\Attribute\DeprecatedAlias;
+use Symfony\Component\Routing\Attribute\Route;
+
+class MultipleDeprecatedAliasRouteController
+{
+    #[Route('/path', name: 'action_with_multiple_deprecated_alias', alias: [
+        new DeprecatedAlias('my_first_alias_deprecated', 'MyFirstBundleFixture', '1.0'),
+        new DeprecatedAlias('my_second_alias_deprecated', 'MySecondBundleFixture', '2.0'),
+        new DeprecatedAlias('my_third_alias_deprecated', 'SurprisedThirdBundleFixture', '3.0'),
+    ])]
+    public function action()
+    {
+    }
+}
diff --git a/Tests/Loader/AttributeClassLoaderTest.php b/Tests/Loader/AttributeClassLoaderTest.php
index afad8731..50a10a16 100644
--- a/Tests/Loader/AttributeClassLoaderTest.php
+++ b/Tests/Loader/AttributeClassLoaderTest.php
@@ -16,8 +16,13 @@
 use Symfony\Component\Routing\Exception\LogicException;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\AbstractClassController;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\ActionPathController;
+use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\AliasClassController;
+use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\AliasInvokableController;
+use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\AliasRouteController;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\BazClass;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\DefaultValueController;
+use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\DeprecatedAliasCustomMessageRouteController;
+use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\DeprecatedAliasRouteController;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\EncodingClass;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\ExplicitLocalizedActionPathController;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\ExtendedRouteOnClassController;
@@ -35,6 +40,7 @@
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\MethodActionControllers;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\MethodsAndSchemes;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\MissingRouteNameController;
+use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\MultipleDeprecatedAliasRouteController;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\NothingButNameController;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\PrefixedActionLocalizedRouteController;
 use Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\PrefixedActionPathController;
@@ -364,4 +370,98 @@ public function testDefaultRouteName()
 
         $this->assertSame('symfony_component_routing_tests_fixtures_attributefixtures_encodingclass_routeàction', $defaultName);
     }
+
+    public function testAliasesOnMethod()
+    {
+        $routes = $this->loader->load(AliasRouteController::class);
+        $route = $routes->get('action_with_alias');
+        $this->assertCount(1, $routes);
+        $this->assertSame('/path', $route->getPath());
+        $this->assertEquals(new Alias('action_with_alias'), $routes->getAlias('alias'));
+        $this->assertEquals(new Alias('action_with_alias'), $routes->getAlias('completely_different_name'));
+    }
+
+    public function testThrowsWithAliasesOnClass()
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Route aliases cannot be used on non-invokable class "Symfony\Component\Routing\Tests\Fixtures\AttributeFixtures\AliasClassController".');
+
+        $this->loader->load(AliasClassController::class);
+    }
+
+    public function testAliasesOnInvokableClass()
+    {
+        $routes = $this->loader->load(AliasInvokableController::class);
+        $route = $routes->get('invokable_path');
+        $this->assertCount(1, $routes);
+        $this->assertSame('/path', $route->getPath());
+        $this->assertEquals(new Alias('invokable_path'), $routes->getAlias('alias'));
+        $this->assertEquals(new Alias('invokable_path'), $routes->getAlias('completely_different_name'));
+    }
+
+    public function testDeprecatedAlias()
+    {
+        $routes = $this->loader->load(DeprecatedAliasRouteController::class);
+        $route = $routes->get('action_with_deprecated_alias');
+        $expected = (new Alias('action_with_deprecated_alias'))
+            ->setDeprecated(
+                'MyBundleFixture',
+                '1.0',
+                'The "%alias_id%" route alias is deprecated. You should stop using it, as it will be removed in the future.'
+            );
+        $actual = $routes->getAlias('my_other_alias_deprecated');
+        $this->assertCount(1, $routes);
+        $this->assertSame('/path', $route->getPath());
+        $this->assertEquals($expected, $actual);
+    }
+
+    public function testDeprecatedAliasWithCustomMessage()
+    {
+        $routes = $this->loader->load(DeprecatedAliasCustomMessageRouteController::class);
+        $route = $routes->get('action_with_deprecated_alias');
+        $expected = (new Alias('action_with_deprecated_alias'))
+            ->setDeprecated(
+                'MyBundleFixture',
+                '1.0',
+                '%alias_id% alias is deprecated.'
+            );
+        $actual = $routes->getAlias('my_other_alias_deprecated');
+        $this->assertCount(1, $routes);
+        $this->assertSame('/path', $route->getPath());
+        $this->assertEquals($expected, $actual);
+    }
+
+    public function testMultipleDeprecatedAlias()
+    {
+        $routes = $this->loader->load(MultipleDeprecatedAliasRouteController::class);
+        $route = $routes->get('action_with_multiple_deprecated_alias');
+        $this->assertCount(1, $routes);
+        $this->assertSame('/path', $route->getPath());
+
+        $dataset = [
+            'my_first_alias_deprecated' => [
+                'package' => 'MyFirstBundleFixture',
+                'version' => '1.0',
+            ],
+            'my_second_alias_deprecated' => [
+                'package' => 'MySecondBundleFixture',
+                'version' => '2.0',
+            ],
+            'my_third_alias_deprecated' => [
+                'package' => 'SurprisedThirdBundleFixture',
+                'version' => '3.0',
+            ],
+        ];
+
+        foreach ($dataset as $aliasName => $aliasData) {
+            $expected = (new Alias('action_with_multiple_deprecated_alias'))
+                ->setDeprecated(
+                    $aliasData['package'],
+                    $aliasData['version'],
+                    'The "%alias_id%" route alias is deprecated. You should stop using it, as it will be removed in the future.'
+                );
+            $actual = $routes->getAlias($aliasName);
+            $this->assertEquals($expected, $actual);
+        }
+    }
 }
diff --git a/Tests/Loader/Psr4DirectoryLoaderTest.php b/Tests/Loader/Psr4DirectoryLoaderTest.php
index 81515b86..0720caca 100644
--- a/Tests/Loader/Psr4DirectoryLoaderTest.php
+++ b/Tests/Loader/Psr4DirectoryLoaderTest.php
@@ -15,6 +15,7 @@
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\Config\Loader\DelegatingLoader;
 use Symfony\Component\Config\Loader\LoaderResolver;
+use Symfony\Component\Routing\Exception\InvalidArgumentException;
 use Symfony\Component\Routing\Loader\AttributeClassLoader;
 use Symfony\Component\Routing\Loader\Psr4DirectoryLoader;
 use Symfony\Component\Routing\Route;
@@ -90,6 +91,34 @@ public static function provideNamespacesThatNeedTrimming(): array
         ];
     }
 
+    /**
+     * @dataProvider provideInvalidPsr4Namespaces
+     */
+    public function testInvalidPsr4Namespace(string $namespace, string $expectedExceptionMessage)
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage($expectedExceptionMessage);
+
+        $this->getLoader()->load(
+            ['path' => 'Psr4Controllers', 'namespace' => $namespace],
+            'attribute'
+        );
+    }
+
+    public static function provideInvalidPsr4Namespaces(): array
+    {
+        return [
+            'slash instead of back-slash' => [
+                'namespace' => 'App\Application/Controllers',
+                'expectedExceptionMessage' => 'Namespace "App\Application/Controllers" is not a valid PSR-4 prefix.',
+            ],
+            'invalid namespace' => [
+                'namespace' => 'App\Contro llers',
+                'expectedExceptionMessage' => 'Namespace "App\Contro llers" is not a valid PSR-4 prefix.',
+            ],
+        ];
+    }
+
     private function loadPsr4Controllers(): RouteCollection
     {
         return $this->getLoader()->load(
diff --git a/Tests/Loader/YamlFileLoaderTest.php b/Tests/Loader/YamlFileLoaderTest.php
index c8bc44e6..4f6ed3a2 100644
--- a/Tests/Loader/YamlFileLoaderTest.php
+++ b/Tests/Loader/YamlFileLoaderTest.php
@@ -503,7 +503,7 @@ public function testPriorityWithHost()
     {
         new LoaderResolver([
             $loader = new YamlFileLoader(new FileLocator(\dirname(__DIR__).'/Fixtures/locale_and_host')),
-            new class() extends AttributeClassLoader {
+            new class extends AttributeClassLoader {
                 protected function configureRoute(
                     Route $route,
                     \ReflectionClass $class,
diff --git a/Tests/Matcher/Dumper/StaticPrefixCollectionTest.php b/Tests/Matcher/Dumper/StaticPrefixCollectionTest.php
index 86e0d0e3..9935ced4 100644
--- a/Tests/Matcher/Dumper/StaticPrefixCollectionTest.php
+++ b/Tests/Matcher/Dumper/StaticPrefixCollectionTest.php
@@ -47,7 +47,7 @@ public static function routeProvider()
 root
 prefix_segment
 leading_segment
-EOF
+EOF,
             ],
             'Nested - small group' => [
                 [
@@ -60,7 +60,7 @@ public static function routeProvider()
 /prefix/segment/
 -> prefix_segment
 -> leading_segment
-EOF
+EOF,
             ],
             'Nested - contains item at intersection' => [
                 [
@@ -73,7 +73,7 @@ public static function routeProvider()
 /prefix/segment/
 -> prefix_segment
 -> leading_segment
-EOF
+EOF,
             ],
             'Simple one level nesting' => [
                 [
@@ -88,7 +88,7 @@ public static function routeProvider()
 -> nested_segment
 -> some_segment
 -> other_segment
-EOF
+EOF,
             ],
             'Retain matching order with groups' => [
                 [
@@ -110,7 +110,7 @@ public static function routeProvider()
 -> dd
 -> ee
 -> ff
-EOF
+EOF,
             ],
             'Retain complex matching order with groups at base' => [
                 [
@@ -142,7 +142,7 @@ public static function routeProvider()
 -> -> ee
 -> -> ff
 -> parent
-EOF
+EOF,
             ],
 
             'Group regardless of segments' => [
@@ -163,7 +163,7 @@ public static function routeProvider()
 -> g1
 -> g2
 -> g3
-EOF
+EOF,
             ],
         ];
     }
diff --git a/Tests/Matcher/UrlMatcherTest.php b/Tests/Matcher/UrlMatcherTest.php
index c426e071..0c2756e4 100644
--- a/Tests/Matcher/UrlMatcherTest.php
+++ b/Tests/Matcher/UrlMatcherTest.php
@@ -1011,7 +1011,30 @@ public function testMapping()
             '_route' => 'a',
             'slug' => 'vienna-2024',
             '_route_mapping' => [
-                'slug' => 'conference',
+                'slug' => [
+                    'conference',
+                    'slug',
+                ],
+            ],
+        ];
+        $this->assertEquals($expected, $matcher->match('/conference/vienna-2024'));
+    }
+
+    public function testMappingwithAlias()
+    {
+        $collection = new RouteCollection();
+        $collection->add('a', new Route('/conference/{conferenceSlug:conference.slug}'));
+
+        $matcher = $this->getUrlMatcher($collection);
+
+        $expected = [
+            '_route' => 'a',
+            'conferenceSlug' => 'vienna-2024',
+            '_route_mapping' => [
+                'conferenceSlug' => [
+                    'conference',
+                    'slug',
+                ],
             ],
         ];
         $this->assertEquals($expected, $matcher->match('/conference/vienna-2024'));
diff --git a/Tests/Requirement/RequirementTest.php b/Tests/Requirement/RequirementTest.php
index 814deadd..d7e0ba07 100644
--- a/Tests/Requirement/RequirementTest.php
+++ b/Tests/Requirement/RequirementTest.php
@@ -137,6 +137,32 @@ public function testDigitsKO(string $digits)
         );
     }
 
+    /**
+     * @testWith    ["67c8b7d295c70befc3070bf2"]
+     *              ["000000000000000000000000"]
+     */
+    public function testMongoDbIdOK(string $id)
+    {
+        $this->assertMatchesRegularExpression(
+            (new Route('/{id}', [], ['id' => Requirement::MONGODB_ID]))->compile()->getRegex(),
+            '/'.$id,
+        );
+    }
+
+    /**
+     * @testWith    ["67C8b7D295C70BEFC3070BF2"]
+     *              ["67c8b7d295c70befc3070bg2"]
+     *              ["67c8b7d295c70befc3070bf2a"]
+     *              ["67c8b7d295c70befc3070bf"]
+     */
+    public function testMongoDbIdKO(string $id)
+    {
+        $this->assertDoesNotMatchRegularExpression(
+            (new Route('/{id}', [], ['id' => Requirement::MONGODB_ID]))->compile()->getRegex(),
+            '/'.$id,
+        );
+    }
+
     /**
      * @testWith    ["1"]
      *              ["42"]
diff --git a/Tests/RouteTest.php b/Tests/RouteTest.php
index b58358a3..34728042 100644
--- a/Tests/RouteTest.php
+++ b/Tests/RouteTest.php
@@ -226,37 +226,48 @@ public function testSerialize()
         $this->assertNotSame($route, $unserialized);
     }
 
-    public function testInlineDefaultAndRequirement()
+    /**
+     * @dataProvider provideInlineDefaultAndRequirementCases
+     */
+    public function testInlineDefaultAndRequirement(Route $route, string $expectedPath, string $expectedHost, array $expectedDefaults, array $expectedRequirements)
+    {
+        self::assertSame($expectedPath, $route->getPath());
+        self::assertSame($expectedHost, $route->getHost());
+        self::assertSame($expectedDefaults, $route->getDefaults());
+        self::assertSame($expectedRequirements, $route->getRequirements());
+    }
+
+    public static function provideInlineDefaultAndRequirementCases(): iterable
     {
-        $this->assertEquals((new Route('/foo/{bar}'))->setDefault('bar', null), new Route('/foo/{bar?}'));
-        $this->assertEquals((new Route('/foo/{bar}'))->setDefault('bar', 'baz'), new Route('/foo/{bar?baz}'));
-        $this->assertEquals((new Route('/foo/{bar}'))->setDefault('bar', 'baz<buz>'), new Route('/foo/{bar?baz<buz>}'));
-        $this->assertEquals((new Route('/foo/{!bar}'))->setDefault('bar', 'baz<buz>'), new Route('/foo/{!bar?baz<buz>}'));
-        $this->assertEquals((new Route('/foo/{bar}'))->setDefault('bar', 'baz'), new Route('/foo/{bar?}', ['bar' => 'baz']));
-
-        $this->assertEquals((new Route('/foo/{bar}'))->setRequirement('bar', '.*'), new Route('/foo/{bar<.*>}'));
-        $this->assertEquals((new Route('/foo/{bar}'))->setRequirement('bar', '>'), new Route('/foo/{bar<>>}'));
-        $this->assertEquals((new Route('/foo/{bar}'))->setRequirement('bar', '\d+'), new Route('/foo/{bar<.*>}', [], ['bar' => '\d+']));
-        $this->assertEquals((new Route('/foo/{bar}'))->setRequirement('bar', '[a-z]{2}'), new Route('/foo/{bar<[a-z]{2}>}'));
-        $this->assertEquals((new Route('/foo/{!bar}'))->setRequirement('bar', '\d+'), new Route('/foo/{!bar<\d+>}'));
-
-        $this->assertEquals((new Route('/foo/{bar}'))->setDefault('bar', null)->setRequirement('bar', '.*'), new Route('/foo/{bar<.*>?}'));
-        $this->assertEquals((new Route('/foo/{bar}'))->setDefault('bar', '<>')->setRequirement('bar', '>'), new Route('/foo/{bar<>>?<>}'));
-
-        $this->assertEquals((new Route('/{foo}/{!bar}'))->setDefaults(['bar' => '<>', 'foo' => '\\'])->setRequirements(['bar' => '\\', 'foo' => '.']), new Route('/{foo<.>?\}/{!bar<\>?<>}'));
-
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setDefault('bar', null), (new Route('/'))->setHost('{bar?}'));
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setDefault('bar', 'baz'), (new Route('/'))->setHost('{bar?baz}'));
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setDefault('bar', 'baz<buz>'), (new Route('/'))->setHost('{bar?baz<buz>}'));
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setDefault('bar', null), (new Route('/', ['bar' => 'baz']))->setHost('{bar?}'));
-
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setRequirement('bar', '.*'), (new Route('/'))->setHost('{bar<.*>}'));
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setRequirement('bar', '>'), (new Route('/'))->setHost('{bar<>>}'));
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setRequirement('bar', '.*'), (new Route('/', [], ['bar' => '\d+']))->setHost('{bar<.*>}'));
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setRequirement('bar', '[a-z]{2}'), (new Route('/'))->setHost('{bar<[a-z]{2}>}'));
-
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setDefault('bar', null)->setRequirement('bar', '.*'), (new Route('/'))->setHost('{bar<.*>?}'));
-        $this->assertEquals((new Route('/'))->setHost('{bar}')->setDefault('bar', '<>')->setRequirement('bar', '>'), (new Route('/'))->setHost('{bar<>>?<>}'));
+        yield [new Route('/foo/{bar?}'), '/foo/{bar}', '', ['bar' => null], []];
+        yield [new Route('/foo/{bar?baz}'), '/foo/{bar}', '', ['bar' => 'baz'], []];
+        yield [new Route('/foo/{bar?baz<buz>}'), '/foo/{bar}', '', ['bar' => 'baz<buz>'], []];
+        yield [new Route('/foo/{!bar?baz<buz>}'), '/foo/{!bar}', '', ['bar' => 'baz<buz>'], []];
+        yield [new Route('/foo/{bar?}', ['bar' => 'baz']), '/foo/{bar}', '', ['bar' => 'baz'], []];
+
+        yield [new Route('/foo/{bar<.*>}'), '/foo/{bar}', '', [], ['bar' => '.*']];
+        yield [new Route('/foo/{bar<>>}'), '/foo/{bar}', '', [], ['bar' => '>']];
+        yield [new Route('/foo/{bar<.*>}', [], ['bar' => '\d+']), '/foo/{bar}', '', [], ['bar' => '\d+']];
+        yield [new Route('/foo/{bar<[a-z]{2}>}'), '/foo/{bar}', '', [], ['bar' => '[a-z]{2}']];
+        yield [new Route('/foo/{!bar<\d+>}'), '/foo/{!bar}', '', [], ['bar' => '\d+']];
+
+        yield [new Route('/foo/{bar<.*>?}'), '/foo/{bar}', '', ['bar' => null], ['bar' => '.*']];
+        yield [new Route('/foo/{bar<>>?<>}'), '/foo/{bar}', '', ['bar' => '<>'], ['bar' => '>']];
+
+        yield [new Route('/{foo<.>?\}/{!bar<\>?<>}'), '/{foo}/{!bar}', '', ['foo' => '\\', 'bar' => '<>'], ['foo' => '.', 'bar' => '\\']];
+
+        yield [new Route('/', host: '{bar?}'), '/', '{bar}', ['bar' => null], []];
+        yield [new Route('/', host: '{bar?baz}'), '/', '{bar}', ['bar' => 'baz'], []];
+        yield [new Route('/', host: '{bar?baz<buz>}'), '/', '{bar}', ['bar' => 'baz<buz>'], []];
+        yield [new Route('/', ['bar' => 'baz'], host: '{bar?}'), '/', '{bar}', ['bar' => null], []];
+
+        yield [new Route('/', host: '{bar<.*>}'), '/', '{bar}', [], ['bar' => '.*']];
+        yield [new Route('/', host: '{bar<>>}'), '/', '{bar}', [], ['bar' => '>']];
+        yield [new Route('/', [], ['bar' => '\d+'], host: '{bar<.*>}'), '/', '{bar}', [], ['bar' => '.*']];
+        yield [new Route('/', host: '{bar<[a-z]{2}>}'), '/', '{bar}', [], ['bar' => '[a-z]{2}']];
+
+        yield [new Route('/', host: '{bar<.*>?}'), '/', '{bar}', ['bar' => null], ['bar' => '.*']];
+        yield [new Route('/', host: '{bar<>>?<>}'), '/', '{bar}', ['bar' => '<>'], ['bar' => '>']];
     }
 
     /**