diff --git a/Compiler/MergeExtensionConfigurationPass.php b/Compiler/MergeExtensionConfigurationPass.php
index c64381886..c182d7cda 100644
--- a/Compiler/MergeExtensionConfigurationPass.php
+++ b/Compiler/MergeExtensionConfigurationPass.php
@@ -79,10 +79,6 @@ public function process(ContainerBuilder $container)
                     $container->getParameterBag()->mergeEnvPlaceholders($resolvingBag);
                 }
 
-                if ($configAvailable) {
-                    BaseNode::resetPlaceholders();
-                }
-
                 throw $e;
             }
 
@@ -95,10 +91,6 @@ public function process(ContainerBuilder $container)
             $container->getParameterBag()->add($parameters);
         }
 
-        if ($configAvailable) {
-            BaseNode::resetPlaceholders();
-        }
-
         $container->addDefinitions($definitions);
         $container->addAliases($aliases);
     }
diff --git a/Compiler/ValidateEnvPlaceholdersPass.php b/Compiler/ValidateEnvPlaceholdersPass.php
index 1a397f209..510e90093 100644
--- a/Compiler/ValidateEnvPlaceholdersPass.php
+++ b/Compiler/ValidateEnvPlaceholdersPass.php
@@ -48,46 +48,42 @@ public function process(ContainerBuilder $container)
 
         $defaultBag = new ParameterBag($resolvingBag->all());
         $envTypes = $resolvingBag->getProvidedTypes();
-        try {
-            foreach ($resolvingBag->getEnvPlaceholders() + $resolvingBag->getUnusedEnvPlaceholders() as $env => $placeholders) {
-                $values = [];
-                if (false === $i = strpos($env, ':')) {
-                    $default = $defaultBag->has("env($env)") ? $defaultBag->get("env($env)") : self::TYPE_FIXTURES['string'];
-                    $defaultType = null !== $default ? get_debug_type($default) : 'string';
-                    $values[$defaultType] = $default;
-                } else {
-                    $prefix = substr($env, 0, $i);
-                    foreach ($envTypes[$prefix] ?? ['string'] as $type) {
-                        $values[$type] = self::TYPE_FIXTURES[$type] ?? null;
-                    }
-                }
-                foreach ($placeholders as $placeholder) {
-                    BaseNode::setPlaceholder($placeholder, $values);
+        foreach ($resolvingBag->getEnvPlaceholders() + $resolvingBag->getUnusedEnvPlaceholders() as $env => $placeholders) {
+            $values = [];
+            if (false === $i = strpos($env, ':')) {
+                $default = $defaultBag->has("env($env)") ? $defaultBag->get("env($env)") : self::TYPE_FIXTURES['string'];
+                $defaultType = null !== $default ? get_debug_type($default) : 'string';
+                $values[$defaultType] = $default;
+            } else {
+                $prefix = substr($env, 0, $i);
+                foreach ($envTypes[$prefix] ?? ['string'] as $type) {
+                    $values[$type] = self::TYPE_FIXTURES[$type] ?? null;
                 }
             }
+            foreach ($placeholders as $placeholder) {
+                BaseNode::setPlaceholder($placeholder, $values);
+            }
+        }
 
-            $processor = new Processor();
-
-            foreach ($extensions as $name => $extension) {
-                if (!($extension instanceof ConfigurationExtensionInterface || $extension instanceof ConfigurationInterface)
-                    || !$config = array_filter($container->getExtensionConfig($name))
-                ) {
-                    // this extension has no semantic configuration or was not called
-                    continue;
-                }
+        $processor = new Processor();
 
-                $config = $resolvingBag->resolveValue($config);
+        foreach ($extensions as $name => $extension) {
+            if (!($extension instanceof ConfigurationExtensionInterface || $extension instanceof ConfigurationInterface)
+                || !$config = array_filter($container->getExtensionConfig($name))
+            ) {
+                // this extension has no semantic configuration or was not called
+                continue;
+            }
 
-                if ($extension instanceof ConfigurationInterface) {
-                    $configuration = $extension;
-                } elseif (null === $configuration = $extension->getConfiguration($config, $container)) {
-                    continue;
-                }
+            $config = $resolvingBag->resolveValue($config);
 
-                $this->extensionConfig[$name] = $processor->processConfiguration($configuration, $config);
+            if ($extension instanceof ConfigurationInterface) {
+                $configuration = $extension;
+            } elseif (null === $configuration = $extension->getConfiguration($config, $container)) {
+                continue;
             }
-        } finally {
-            BaseNode::resetPlaceholders();
+
+            $this->extensionConfig[$name] = $processor->processConfiguration($configuration, $config);
         }
 
         $resolvingBag->clearUnusedEnvPlaceholders();
diff --git a/Container.php b/Container.php
index 0532120ad..fc38cd93a 100644
--- a/Container.php
+++ b/Container.php
@@ -103,7 +103,7 @@ public function getParameterBag(): ParameterBagInterface
     /**
      * Gets a parameter.
      *
-     * @return array|bool|string|int|float|null
+     * @return array|bool|string|int|float|\UnitEnum|null
      *
      * @throws InvalidArgumentException if the parameter is not defined
      */
@@ -117,7 +117,7 @@ public function hasParameter(string $name): bool
         return $this->parameterBag->has($name);
     }
 
-    public function setParameter(string $name, array|bool|string|int|float|null $value)
+    public function setParameter(string $name, array|bool|string|int|float|\UnitEnum|null $value)
     {
         $this->parameterBag->set($name, $value);
     }
diff --git a/ContainerInterface.php b/ContainerInterface.php
index aa5d6b317..cad44026c 100644
--- a/ContainerInterface.php
+++ b/ContainerInterface.php
@@ -48,7 +48,7 @@ public function has(string $id): bool;
     public function initialized(string $id): bool;
 
     /**
-     * @return array|bool|string|int|float|null
+     * @return array|bool|string|int|float|\UnitEnum|null
      *
      * @throws InvalidArgumentException if the parameter is not defined
      */
@@ -56,5 +56,5 @@ public function getParameter(string $name);
 
     public function hasParameter(string $name): bool;
 
-    public function setParameter(string $name, array|bool|string|int|float|null $value);
+    public function setParameter(string $name, array|bool|string|int|float|\UnitEnum|null $value);
 }
diff --git a/Dumper/PhpDumper.php b/Dumper/PhpDumper.php
index ddb9b195a..3f50561a5 100644
--- a/Dumper/PhpDumper.php
+++ b/Dumper/PhpDumper.php
@@ -334,7 +334,7 @@ class %s extends {$options['class']}
                     if (!$class || str_contains($class, '$') || \in_array($class, ['int', 'float', 'string', 'bool', 'resource', 'object', 'array', 'null', 'callable', 'iterable', 'mixed', 'void'], true)) {
                         continue;
                     }
-                    if (!(class_exists($class, false) || interface_exists($class, false) || trait_exists($class, false)) || (new \ReflectionClass($class))->isUserDefined()) {
+                    if (!(class_exists($class, false) || interface_exists($class, false) || trait_exists($class, false)) || ((new \ReflectionClass($class))->isUserDefined() && !\in_array($class, ['Attribute', 'JsonException', 'ReturnTypeWillChange', 'Stringable', 'UnhandledMatchError', 'ValueError'], true))) {
                         $code[$options['class'].'.preload.php'] .= sprintf("\$classes[] = '%s';\n", $class);
                     }
                 }
@@ -1491,10 +1491,11 @@ private function addDefaultParametersMethod(): string
             if ($key !== $resolvedKey = $this->container->resolveEnvPlaceholders($key)) {
                 throw new InvalidArgumentException(sprintf('Parameter name cannot use env parameters: "%s".', $resolvedKey));
             }
-            $export = $this->exportParameters([$value]);
+            $hasEnum = false;
+            $export = $this->exportParameters([$value], '', 12, $hasEnum);
             $export = explode('0 => ', substr(rtrim($export, " ]\n"), 2, -1), 2);
 
-            if (preg_match("/\\\$this->(?:getEnv\('(?:[-.\w]*+:)*+\w++'\)|targetDir\.'')/", $export[1])) {
+            if ($hasEnum || preg_match("/\\\$this->(?:getEnv\('(?:[-.\w]*+:)*+\w++'\)|targetDir\.'')/", $export[1])) {
                 $dynamicPhp[$key] = sprintf('%scase %s: $value = %s; break;', $export[0], $this->export($key), $export[1]);
             } else {
                 $php[] = sprintf('%s%s => %s,', $export[0], $this->export($key), $export[1]);
@@ -1504,7 +1505,7 @@ private function addDefaultParametersMethod(): string
 
         $code = <<<'EOF'
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (isset($this->buildParameters[$name])) {
             return $this->buildParameters[$name];
@@ -1595,12 +1596,12 @@ protected function getDefaultParameters(): array
     /**
      * @throws InvalidArgumentException
      */
-    private function exportParameters(array $parameters, string $path = '', int $indent = 12): string
+    private function exportParameters(array $parameters, string $path = '', int $indent = 12, bool &$hasEnum = false): string
     {
         $php = [];
         foreach ($parameters as $key => $value) {
             if (\is_array($value)) {
-                $value = $this->exportParameters($value, $path.'/'.$key, $indent + 4);
+                $value = $this->exportParameters($value, $path.'/'.$key, $indent + 4, $hasEnum);
             } elseif ($value instanceof ArgumentInterface) {
                 throw new InvalidArgumentException(sprintf('You cannot dump a container with parameters that contain special arguments. "%s" found in "%s".', get_debug_type($value), $path.'/'.$key));
             } elseif ($value instanceof Variable) {
@@ -1611,6 +1612,9 @@ private function exportParameters(array $parameters, string $path = '', int $ind
                 throw new InvalidArgumentException(sprintf('You cannot dump a container with parameters that contain references to other services (reference to service "%s" found in "%s").', $value, $path.'/'.$key));
             } elseif ($value instanceof Expression) {
                 throw new InvalidArgumentException(sprintf('You cannot dump a container with parameters that contain expressions. Expression "%s" found in "%s".', $value, $path.'/'.$key));
+            } elseif ($value instanceof \UnitEnum) {
+                $hasEnum = true;
+                $value = sprintf('\%s::%s', \get_class($value), $value->name);
             } else {
                 $value = $this->export($value);
             }
diff --git a/Loader/Configurator/ParametersConfigurator.php b/Loader/Configurator/ParametersConfigurator.php
index d3e9fd9e7..302255b04 100644
--- a/Loader/Configurator/ParametersConfigurator.php
+++ b/Loader/Configurator/ParametersConfigurator.php
@@ -12,6 +12,8 @@
 namespace Symfony\Component\DependencyInjection\Loader\Configurator;
 
 use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
+use Symfony\Component\ExpressionLanguage\Expression;
 
 /**
  * @author Nicolas Grekas <p@tchwork.com>
@@ -32,6 +34,10 @@ public function __construct(ContainerBuilder $container)
      */
     final public function set(string $name, mixed $value): static
     {
+        if ($value instanceof Expression) {
+            throw new InvalidArgumentException(sprintf('Using an expression in parameter "%s" is not allowed.', $name));
+        }
+
         $this->container->setParameter($name, static::processValue($value, true));
 
         return $this;
diff --git a/Loader/YamlFileLoader.php b/Loader/YamlFileLoader.php
index 2c7f41364..8d7c3ab6e 100644
--- a/Loader/YamlFileLoader.php
+++ b/Loader/YamlFileLoader.php
@@ -883,6 +883,10 @@ private function resolveServices(mixed $value, string $file, bool $isParameter =
                 $value[$k] = $this->resolveServices($v, $file, $isParameter);
             }
         } elseif (\is_string($value) && str_starts_with($value, '@=')) {
+            if ($isParameter) {
+                throw new InvalidArgumentException(sprintf('Using expressions in parameters is not allowed in "%s".', $file));
+            }
+
             if (!class_exists(Expression::class)) {
                 throw new \LogicException('The "@=" expression syntax cannot be used without the ExpressionLanguage component. Try running "composer require symfony/expression-language".');
             }
diff --git a/ParameterBag/ContainerBag.php b/ParameterBag/ContainerBag.php
index d6559d894..ec5876f50 100644
--- a/ParameterBag/ContainerBag.php
+++ b/ParameterBag/ContainerBag.php
@@ -36,7 +36,7 @@ public function all(): array
     /**
      * {@inheritdoc}
      */
-    public function get(string $name): array|bool|string|int|float|null
+    public function get(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         return $this->container->getParameter($name);
     }
diff --git a/ParameterBag/FrozenParameterBag.php b/ParameterBag/FrozenParameterBag.php
index 0e57d3379..2a617ffd8 100644
--- a/ParameterBag/FrozenParameterBag.php
+++ b/ParameterBag/FrozenParameterBag.php
@@ -53,7 +53,7 @@ public function add(array $parameters)
     /**
      * {@inheritdoc}
      */
-    public function set(string $name, array|bool|string|int|float|null $value)
+    public function set(string $name, array|bool|string|int|float|\UnitEnum|null $value)
     {
         throw new LogicException('Impossible to call set() on a frozen ParameterBag.');
     }
diff --git a/ParameterBag/ParameterBag.php b/ParameterBag/ParameterBag.php
index c29a5ce0c..bfeee834d 100644
--- a/ParameterBag/ParameterBag.php
+++ b/ParameterBag/ParameterBag.php
@@ -59,7 +59,7 @@ public function all(): array
     /**
      * {@inheritdoc}
      */
-    public function get(string $name): array|bool|string|int|float|null
+    public function get(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!\array_key_exists($name, $this->parameters)) {
             if (!$name) {
@@ -99,7 +99,7 @@ public function get(string $name): array|bool|string|int|float|null
     /**
      * {@inheritdoc}
      */
-    public function set(string $name, array|bool|string|int|float|null $value)
+    public function set(string $name, array|bool|string|int|float|\UnitEnum|null $value)
     {
         $this->parameters[$name] = $value;
     }
diff --git a/ParameterBag/ParameterBagInterface.php b/ParameterBag/ParameterBagInterface.php
index 7e276fd8f..0ac3323ff 100644
--- a/ParameterBag/ParameterBagInterface.php
+++ b/ParameterBag/ParameterBagInterface.php
@@ -45,7 +45,7 @@ public function all(): array;
      *
      * @throws ParameterNotFoundException if the parameter is not defined
      */
-    public function get(string $name): array|bool|string|int|float|null;
+    public function get(string $name): array|bool|string|int|float|\UnitEnum|null;
 
     /**
      * Removes a parameter.
@@ -57,7 +57,7 @@ public function remove(string $name);
      *
      * @throws LogicException if the parameter cannot be set
      */
-    public function set(string $name, array|bool|string|int|float|null $value);
+    public function set(string $name, array|bool|string|int|float|\UnitEnum|null $value);
 
     /**
      * Returns true if a parameter name is defined.
diff --git a/Tests/Dumper/PhpDumperTest.php b/Tests/Dumper/PhpDumperTest.php
index 209079fc7..fbcf4459c 100644
--- a/Tests/Dumper/PhpDumperTest.php
+++ b/Tests/Dumper/PhpDumperTest.php
@@ -24,6 +24,7 @@
 use Symfony\Component\DependencyInjection\Argument\ServiceLocatorArgument;
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
 use Symfony\Component\DependencyInjection\Compiler\PassConfig;
+use Symfony\Component\DependencyInjection\Container;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\ContainerInterface as SymfonyContainerInterface;
 use Symfony\Component\DependencyInjection\Definition;
@@ -1219,16 +1220,37 @@ public function testDumpHandlesEnumeration()
             ->setPublic(true)
             ->addArgument(FooUnitEnum::BAR);
 
+        $container->setParameter('unit_enum', FooUnitEnum::BAR);
+        $container->setParameter('enum_array', [FooUnitEnum::BAR, FooUnitEnum::FOO]);
         $container->compile();
 
         $dumper = new PhpDumper($container);
-        eval('?>'.$dumper->dump([
+        eval('?>'.$dumpedContainer = $dumper->dump([
             'class' => 'Symfony_DI_PhpDumper_Test_Enumeration',
         ]));
 
+        /** @var Container $container */
         $container = new \Symfony_DI_PhpDumper_Test_Enumeration();
 
         $this->assertSame(FooUnitEnum::BAR, $container->get('foo')->getBar());
+        $this->assertSame(FooUnitEnum::BAR, $container->getParameter('unit_enum'));
+        $this->assertSame([FooUnitEnum::BAR, FooUnitEnum::FOO], $container->getParameter('enum_array'));
+        $this->assertStringMatchesFormat(<<<'PHP'
+%A
+    private function getDynamicParameter(string $name)
+    {
+        switch ($name) {
+            case 'unit_enum': $value = \Symfony\Component\DependencyInjection\Tests\Fixtures\FooUnitEnum::BAR; break;
+            case 'enum_array': $value = [
+                0 => \Symfony\Component\DependencyInjection\Tests\Fixtures\FooUnitEnum::BAR,
+                1 => \Symfony\Component\DependencyInjection\Tests\Fixtures\FooUnitEnum::FOO,
+            ]; break;
+            default: throw new InvalidArgumentException(sprintf('The dynamic parameter "%s" must be defined.', $name));
+        }
+%A
+PHP
+            , $dumpedContainer
+        );
     }
 
     public function testUninitializedSyntheticReference()
diff --git a/Tests/Dumper/XmlDumperTest.php b/Tests/Dumper/XmlDumperTest.php
index 067db14e9..deca0a196 100644
--- a/Tests/Dumper/XmlDumperTest.php
+++ b/Tests/Dumper/XmlDumperTest.php
@@ -49,13 +49,6 @@ public function testExportParameters()
         $this->assertXmlStringEqualsXmlFile(self::$fixturesPath.'/xml/services8.xml', $dumper->dump(), '->dump() dumps parameters');
     }
 
-    public function testAddParameters()
-    {
-        $container = include self::$fixturesPath.'//containers/container8.php';
-        $dumper = new XmlDumper($container);
-        $this->assertXmlStringEqualsXmlFile(self::$fixturesPath.'/xml/services8.xml', $dumper->dump(), '->dump() dumps parameters');
-    }
-
     public function testAddService()
     {
         $container = include self::$fixturesPath.'/containers/container9.php';
@@ -255,6 +248,9 @@ public function testDumpHandlesEnumeration()
             ->setPublic(true)
             ->addArgument(FooUnitEnum::BAR);
 
+        $container->setParameter('unit_enum', FooUnitEnum::BAR);
+        $container->setParameter('enum_array', [FooUnitEnum::BAR, FooUnitEnum::FOO]);
+
         $container->compile();
         $dumper = new XmlDumper($container);
 
diff --git a/Tests/Dumper/YamlDumperTest.php b/Tests/Dumper/YamlDumperTest.php
index 0fed70bb0..1bfd222ed 100644
--- a/Tests/Dumper/YamlDumperTest.php
+++ b/Tests/Dumper/YamlDumperTest.php
@@ -144,6 +144,9 @@ public function testDumpHandlesEnumeration()
             ->setPublic(true)
             ->addArgument(FooUnitEnum::BAR);
 
+        $container->setParameter('unit_enum', FooUnitEnum::BAR);
+        $container->setParameter('enum_array', [FooUnitEnum::BAR, FooUnitEnum::FOO]);
+
         $container->compile();
         $dumper = new YamlDumper($container);
 
diff --git a/Tests/Fixtures/FooUnitEnum.php b/Tests/Fixtures/FooUnitEnum.php
index d51cf9c99..e6ce96391 100644
--- a/Tests/Fixtures/FooUnitEnum.php
+++ b/Tests/Fixtures/FooUnitEnum.php
@@ -5,4 +5,5 @@
 enum FooUnitEnum
 {
     case BAR;
+    case FOO;
 }
diff --git a/Tests/Fixtures/php/services10.php b/Tests/Fixtures/php/services10.php
index c0d747a7a..41ac6df9c 100644
--- a/Tests/Fixtures/php/services10.php
+++ b/Tests/Fixtures/php/services10.php
@@ -48,7 +48,7 @@ protected function getTestService()
         return $this->services['test'] = new \stdClass(['only dot' => '.', 'concatenation as value' => '.\'\'.', 'concatenation from the start value' => '\'\'.', '.' => 'dot as a key', '.\'\'.' => 'concatenation as a key', '\'\'.' => 'concatenation from the start key', 'optimize concatenation' => 'string1-string2', 'optimize concatenation with empty string' => 'string1string2', 'optimize concatenation from the start' => 'start', 'optimize concatenation at the end' => 'end', 'new line' => 'string with '."\n".'new line']);
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services12.php b/Tests/Fixtures/php/services12.php
index ffa52cb3c..275f553df 100644
--- a/Tests/Fixtures/php/services12.php
+++ b/Tests/Fixtures/php/services12.php
@@ -48,7 +48,7 @@ protected function getTestService()
         return $this->services['test'] = new \stdClass(('file://'.\dirname(__DIR__, 1)), [('file://'.\dirname(__DIR__, 1)) => (\dirname(__DIR__, 2).'/')]);
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services19.php b/Tests/Fixtures/php/services19.php
index 0c6fb392d..038ed1460 100644
--- a/Tests/Fixtures/php/services19.php
+++ b/Tests/Fixtures/php/services19.php
@@ -63,7 +63,7 @@ protected function getServiceWithMethodCallAndFactoryService()
         return $instance;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services26.php b/Tests/Fixtures/php/services26.php
index 3e98b3507..4ae8d63c7 100644
--- a/Tests/Fixtures/php/services26.php
+++ b/Tests/Fixtures/php/services26.php
@@ -59,7 +59,7 @@ protected function getTestService()
         return $this->services['test'] = new ${($_ = $this->getEnv('FOO')) && false ?: "_"}($this->getEnv('Bar'), 'foo'.$this->getEnv('string:FOO').'baz', $this->getEnv('int:Baz'));
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services8.php b/Tests/Fixtures/php/services8.php
index 1946a9e52..a2928c29f 100644
--- a/Tests/Fixtures/php/services8.php
+++ b/Tests/Fixtures/php/services8.php
@@ -35,7 +35,7 @@ public function isCompiled(): bool
         return true;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services9_as_files.txt b/Tests/Fixtures/php/services9_as_files.txt
index 3f93e3037..e91f08f4f 100644
--- a/Tests/Fixtures/php/services9_as_files.txt
+++ b/Tests/Fixtures/php/services9_as_files.txt
@@ -821,7 +821,7 @@ class ProjectServiceContainer extends Container
         return $instance;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (isset($this->buildParameters[$name])) {
             return $this->buildParameters[$name];
diff --git a/Tests/Fixtures/php/services9_compiled.php b/Tests/Fixtures/php/services9_compiled.php
index 3ec66320c..9e09743da 100644
--- a/Tests/Fixtures/php/services9_compiled.php
+++ b/Tests/Fixtures/php/services9_compiled.php
@@ -419,7 +419,7 @@ protected function getFactorySimpleService()
         return new \SimpleFactoryClass('foo');
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services9_inlined_factories.txt b/Tests/Fixtures/php/services9_inlined_factories.txt
index eb6347e19..2447367de 100644
--- a/Tests/Fixtures/php/services9_inlined_factories.txt
+++ b/Tests/Fixtures/php/services9_inlined_factories.txt
@@ -474,7 +474,7 @@ class ProjectServiceContainer extends Container
         return new \SimpleFactoryClass('foo');
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (isset($this->buildParameters[$name])) {
             return $this->buildParameters[$name];
diff --git a/Tests/Fixtures/php/services9_lazy_inlined_factories.txt b/Tests/Fixtures/php/services9_lazy_inlined_factories.txt
index 822240560..c3487ac0c 100644
--- a/Tests/Fixtures/php/services9_lazy_inlined_factories.txt
+++ b/Tests/Fixtures/php/services9_lazy_inlined_factories.txt
@@ -94,7 +94,7 @@ class ProjectServiceContainer extends Container
         return new \Bar\FooClass(new \Bar\FooLazyClass());
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (isset($this->buildParameters[$name])) {
             return $this->buildParameters[$name];
diff --git a/Tests/Fixtures/php/services_array_params.php b/Tests/Fixtures/php/services_array_params.php
index 8bab13be9..3295d21ce 100644
--- a/Tests/Fixtures/php/services_array_params.php
+++ b/Tests/Fixtures/php/services_array_params.php
@@ -52,7 +52,7 @@ protected function getBarService()
         return $instance;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_base64_env.php b/Tests/Fixtures/php/services_base64_env.php
index c5e3f258a..cee2a435a 100644
--- a/Tests/Fixtures/php/services_base64_env.php
+++ b/Tests/Fixtures/php/services_base64_env.php
@@ -35,7 +35,7 @@ public function isCompiled(): bool
         return true;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_csv_env.php b/Tests/Fixtures/php/services_csv_env.php
index 11d11c8d6..054fe1ea8 100644
--- a/Tests/Fixtures/php/services_csv_env.php
+++ b/Tests/Fixtures/php/services_csv_env.php
@@ -35,7 +35,7 @@ public function isCompiled(): bool
         return true;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_default_env.php b/Tests/Fixtures/php/services_default_env.php
index 0448e7b21..82044d62d 100644
--- a/Tests/Fixtures/php/services_default_env.php
+++ b/Tests/Fixtures/php/services_default_env.php
@@ -35,7 +35,7 @@ public function isCompiled(): bool
         return true;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_env_in_id.php b/Tests/Fixtures/php/services_env_in_id.php
index dd4b93499..e8f3ddb8e 100644
--- a/Tests/Fixtures/php/services_env_in_id.php
+++ b/Tests/Fixtures/php/services_env_in_id.php
@@ -67,7 +67,7 @@ protected function getFooService()
         return $this->services['foo'] = new \stdClass(($this->privates['bar_%env(BAR)%'] ?? ($this->privates['bar_%env(BAR)%'] = new \stdClass())), ['baz_'.$this->getEnv('string:BAR') => new \stdClass()]);
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_errored_definition.php b/Tests/Fixtures/php/services_errored_definition.php
index 4b21be584..621a04c9e 100644
--- a/Tests/Fixtures/php/services_errored_definition.php
+++ b/Tests/Fixtures/php/services_errored_definition.php
@@ -419,7 +419,7 @@ protected function getFactorySimpleService()
         return new \SimpleFactoryClass('foo');
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_inline_requires.php b/Tests/Fixtures/php/services_inline_requires.php
index 8271065a5..50f874d8f 100644
--- a/Tests/Fixtures/php/services_inline_requires.php
+++ b/Tests/Fixtures/php/services_inline_requires.php
@@ -87,7 +87,7 @@ protected function getC2Service()
         return $this->services['Symfony\\Component\\DependencyInjection\\Tests\\Fixtures\\includes\\HotPath\\C2'] = new \Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C2(new \Symfony\Component\DependencyInjection\Tests\Fixtures\includes\HotPath\C3());
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_json_env.php b/Tests/Fixtures/php/services_json_env.php
index 82057518e..ef9b95f2e 100644
--- a/Tests/Fixtures/php/services_json_env.php
+++ b/Tests/Fixtures/php/services_json_env.php
@@ -35,7 +35,7 @@ public function isCompiled(): bool
         return true;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_query_string_env.php b/Tests/Fixtures/php/services_query_string_env.php
index 83e8d7bc6..6d147b930 100644
--- a/Tests/Fixtures/php/services_query_string_env.php
+++ b/Tests/Fixtures/php/services_query_string_env.php
@@ -35,7 +35,7 @@ public function isCompiled(): bool
         return true;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_rot13_env.php b/Tests/Fixtures/php/services_rot13_env.php
index 27c2a5795..a17f9ed56 100644
--- a/Tests/Fixtures/php/services_rot13_env.php
+++ b/Tests/Fixtures/php/services_rot13_env.php
@@ -72,7 +72,7 @@ protected function getContainer_EnvVarProcessorsLocatorService()
         ]);
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_unsupported_characters.php b/Tests/Fixtures/php/services_unsupported_characters.php
index 68d442f63..7e03f763a 100644
--- a/Tests/Fixtures/php/services_unsupported_characters.php
+++ b/Tests/Fixtures/php/services_unsupported_characters.php
@@ -70,7 +70,7 @@ protected function getFooohnoService()
         return $this->services['foo*/oh-no'] = new \FooClass();
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/php/services_url_env.php b/Tests/Fixtures/php/services_url_env.php
index ff5fd5ccf..b370f8db7 100644
--- a/Tests/Fixtures/php/services_url_env.php
+++ b/Tests/Fixtures/php/services_url_env.php
@@ -35,7 +35,7 @@ public function isCompiled(): bool
         return true;
     }
 
-    public function getParameter(string $name): array|string|int|float|bool|null
+    public function getParameter(string $name): array|bool|string|int|float|\UnitEnum|null
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || \array_key_exists($name, $this->parameters))) {
             throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
diff --git a/Tests/Fixtures/xml/services_with_enumeration.xml b/Tests/Fixtures/xml/services_with_enumeration.xml
index 30e80f005..3f26d968a 100644
--- a/Tests/Fixtures/xml/services_with_enumeration.xml
+++ b/Tests/Fixtures/xml/services_with_enumeration.xml
@@ -1,5 +1,12 @@
 <?xml version="1.0" encoding="utf-8"?>
 <container xmlns="http://symfony.com/schema/dic/services" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services https://symfony.com/schema/dic/services/services-1.0.xsd">
+  <parameters>
+    <parameter key="unit_enum" type="constant">Symfony\Component\DependencyInjection\Tests\Fixtures\FooUnitEnum::BAR</parameter>
+    <parameter key="enum_array" type="collection">
+      <parameter type="constant">Symfony\Component\DependencyInjection\Tests\Fixtures\FooUnitEnum::BAR</parameter>
+      <parameter type="constant">Symfony\Component\DependencyInjection\Tests\Fixtures\FooUnitEnum::FOO</parameter>
+    </parameter>
+  </parameters>
   <services>
     <service id="service_container" class="Symfony\Component\DependencyInjection\ContainerInterface" public="true" synthetic="true"/>
     <service id="Symfony\Component\DependencyInjection\Tests\Fixtures\FooClassWithEnumAttribute" class="Symfony\Component\DependencyInjection\Tests\Fixtures\FooClassWithEnumAttribute" public="true">
diff --git a/Tests/Fixtures/yaml/services_with_enumeration.yml b/Tests/Fixtures/yaml/services_with_enumeration.yml
index 46bf505d4..0d3357033 100644
--- a/Tests/Fixtures/yaml/services_with_enumeration.yml
+++ b/Tests/Fixtures/yaml/services_with_enumeration.yml
@@ -1,3 +1,6 @@
+parameters:
+    unit_enum: !php/const Symfony\Component\DependencyInjection\Tests\Fixtures\FooUnitEnum::BAR
+    enum_array: [!php/const Symfony\Component\DependencyInjection\Tests\Fixtures\FooUnitEnum::BAR, !php/const Symfony\Component\DependencyInjection\Tests\Fixtures\FooUnitEnum::FOO]
 
 services:
     service_container: