diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/AbstractConfigCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/AbstractConfigCommand.php
index cc1b858abb33..fe0d60b5554f 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/AbstractConfigCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/AbstractConfigCommand.php
@@ -52,6 +52,9 @@ protected function listBundles($output)
         }
     }
 
+    /**
+     * @return ExtensionInterface
+     */
     protected function findExtension($name)
     {
         $bundles = $this->initializeBundles();
diff --git a/src/Symfony/Bundle/FrameworkBundle/Routing/DelegatingLoader.php b/src/Symfony/Bundle/FrameworkBundle/Routing/DelegatingLoader.php
index 08690fa3dd07..aafcbd63afa7 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Routing/DelegatingLoader.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Routing/DelegatingLoader.php
@@ -40,7 +40,7 @@ public function __construct(LoaderResolverInterface $resolver, array $defaultOpt
     /**
      * {@inheritdoc}
      */
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         if ($this->loading) {
             // This can happen if a fatal error occurs in parent::load().
diff --git a/src/Symfony/Bundle/FrameworkBundle/composer.json b/src/Symfony/Bundle/FrameworkBundle/composer.json
index 6bc99db6af6c..a628750c5271 100644
--- a/src/Symfony/Bundle/FrameworkBundle/composer.json
+++ b/src/Symfony/Bundle/FrameworkBundle/composer.json
@@ -19,7 +19,7 @@
         "php": "^7.2.9",
         "ext-xml": "*",
         "symfony/cache": "^4.4|^5.0",
-        "symfony/config": "^4.4|^5.0",
+        "symfony/config": "^5.0",
         "symfony/dependency-injection": "^4.4|^5.0",
         "symfony/error-catcher": "^4.4|^5.0",
         "symfony/http-foundation": "^4.4|^5.0",
diff --git a/src/Symfony/Component/Config/ConfigCacheFactory.php b/src/Symfony/Component/Config/ConfigCacheFactory.php
index bcec95c11d9c..11fd3cb3a2d4 100644
--- a/src/Symfony/Component/Config/ConfigCacheFactory.php
+++ b/src/Symfony/Component/Config/ConfigCacheFactory.php
@@ -35,12 +35,8 @@ public function __construct(bool $debug)
     /**
      * {@inheritdoc}
      */
-    public function cache(string $file, $callback)
+    public function cache(string $file, callable $callback)
     {
-        if (!\is_callable($callback)) {
-            throw new \InvalidArgumentException(sprintf('Invalid type for callback argument. Expected callable, but got "%s".', \gettype($callback)));
-        }
-
         $cache = new ConfigCache($file, $this->debug);
         if (!$cache->isFresh()) {
             $callback($cache);
diff --git a/src/Symfony/Component/Config/ConfigCacheFactoryInterface.php b/src/Symfony/Component/Config/ConfigCacheFactoryInterface.php
index 255b85a6575a..7dfa0f243797 100644
--- a/src/Symfony/Component/Config/ConfigCacheFactoryInterface.php
+++ b/src/Symfony/Component/Config/ConfigCacheFactoryInterface.php
@@ -28,5 +28,5 @@ interface ConfigCacheFactoryInterface
      *
      * @return ConfigCacheInterface The cache instance
      */
-    public function cache(string $file, $callable);
+    public function cache(string $file, callable $callable);
 }
diff --git a/src/Symfony/Component/Config/Definition/ArrayNode.php b/src/Symfony/Component/Config/Definition/ArrayNode.php
index 9fabdd5628a4..74167bbf6a97 100644
--- a/src/Symfony/Component/Config/Definition/ArrayNode.php
+++ b/src/Symfony/Component/Config/Definition/ArrayNode.php
@@ -129,16 +129,16 @@ public function setAllowNewKeys(bool $allow)
      */
     public function setPerformDeepMerging(bool $boolean)
     {
-        $this->performDeepMerging = (bool) $boolean;
+        $this->performDeepMerging = $boolean;
     }
 
     /**
-     * Whether extra keys should just be ignore without an exception.
+     * Whether extra keys should just be ignored without an exception.
      *
      * @param bool $boolean To allow extra keys
      * @param bool $remove  To remove extra keys
      */
-    public function setIgnoreExtraKeys(bool $boolean, $remove = true)
+    public function setIgnoreExtraKeys(bool $boolean, bool $remove = true)
     {
         $this->ignoreExtraKeys = $boolean;
         $this->removeExtraKeys = $this->ignoreExtraKeys && $remove;
diff --git a/src/Symfony/Component/Config/Definition/BaseNode.php b/src/Symfony/Component/Config/Definition/BaseNode.php
index 39511c15c6b8..02f816313e68 100644
--- a/src/Symfony/Component/Config/Definition/BaseNode.php
+++ b/src/Symfony/Component/Config/Definition/BaseNode.php
@@ -97,17 +97,17 @@ public static function resetPlaceholders(): void
         self::$placeholders = [];
     }
 
-    public function setAttribute($key, $value)
+    public function setAttribute(string $key, $value)
     {
         $this->attributes[$key] = $value;
     }
 
-    public function getAttribute($key, $default = null)
+    public function getAttribute(string $key, $default = null)
     {
         return isset($this->attributes[$key]) ? $this->attributes[$key] : $default;
     }
 
-    public function hasAttribute($key)
+    public function hasAttribute(string $key)
     {
         return isset($this->attributes[$key]);
     }
@@ -122,17 +122,15 @@ public function setAttributes(array $attributes)
         $this->attributes = $attributes;
     }
 
-    public function removeAttribute($key)
+    public function removeAttribute(string $key)
     {
         unset($this->attributes[$key]);
     }
 
     /**
      * Sets an info message.
-     *
-     * @param string $info
      */
-    public function setInfo($info)
+    public function setInfo(string $info)
     {
         $this->setAttribute('info', $info);
     }
@@ -183,9 +181,9 @@ public function addEquivalentValue($originalValue, $equivalentValue)
      *
      * @param bool $boolean Required node
      */
-    public function setRequired($boolean)
+    public function setRequired(bool $boolean)
     {
-        $this->required = (bool) $boolean;
+        $this->required = $boolean;
     }
 
     /**
@@ -193,22 +191,18 @@ public function setRequired($boolean)
      *
      * You can use %node% and %path% placeholders in your message to display,
      * respectively, the node name and its complete path.
-     *
-     * @param string|null $message Deprecated message
      */
-    public function setDeprecated($message)
+    public function setDeprecated(?string $message)
     {
         $this->deprecationMessage = $message;
     }
 
     /**
      * Sets if this node can be overridden.
-     *
-     * @param bool $allow
      */
-    public function setAllowOverwrite($allow)
+    public function setAllowOverwrite(bool $allow)
     {
-        $this->allowOverwrite = (bool) $allow;
+        $this->allowOverwrite = $allow;
     }
 
     /**
@@ -257,7 +251,7 @@ public function isDeprecated()
      *
      * @return string
      */
-    public function getDeprecationMessage($node, $path)
+    public function getDeprecationMessage(string $node, string $path)
     {
         return strtr($this->deprecationMessage, ['%node%' => $node, '%path%' => $path]);
     }
@@ -366,9 +360,9 @@ final public function normalize($value)
     /**
      * Normalizes the value before any other normalization is applied.
      *
-     * @param $value
+     * @param mixed $value
      *
-     * @return The normalized array value
+     * @return mixed The normalized array value
      */
     protected function preNormalize($value)
     {
diff --git a/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php b/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
index e40d97b2fb89..f2a5148d7249 100644
--- a/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
+++ b/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
@@ -66,11 +66,9 @@ public function children()
     /**
      * Sets a prototype for child nodes.
      *
-     * @param string $type The type of node
-     *
      * @return NodeDefinition
      */
-    public function prototype($type)
+    public function prototype(string $type)
     {
         return $this->prototype = $this->getNodeBuilder()->node(null, $type)->setParent($this);
     }
@@ -194,12 +192,12 @@ public function disallowNewKeysInSubsequentConfigs()
     /**
      * Sets a normalization rule for XML configurations.
      *
-     * @param string $singular The key to remap
-     * @param string $plural   The plural of the key for irregular plurals
+     * @param string      $singular The key to remap
+     * @param string|null $plural   The plural of the key for irregular plurals
      *
      * @return $this
      */
-    public function fixXmlConfig($singular, $plural = null)
+    public function fixXmlConfig(string $singular, string $plural = null)
     {
         $this->normalization()->remap($singular, $plural);
 
@@ -234,7 +232,7 @@ public function fixXmlConfig($singular, $plural = null)
      *
      * @return $this
      */
-    public function useAttributeAsKey($name, $removeKeyItem = true)
+    public function useAttributeAsKey(string $name, bool $removeKeyItem = true)
     {
         $this->key = $name;
         $this->removeKeyItem = $removeKeyItem;
@@ -245,11 +243,9 @@ public function useAttributeAsKey($name, $removeKeyItem = true)
     /**
      * Sets whether the node can be unset.
      *
-     * @param bool $allow
-     *
      * @return $this
      */
-    public function canBeUnset($allow = true)
+    public function canBeUnset(bool $allow = true)
     {
         $this->merge()->allowUnset($allow);
 
@@ -341,7 +337,7 @@ public function performNoDeepMerging()
      *
      * @return $this
      */
-    public function ignoreExtraKeys($remove = true)
+    public function ignoreExtraKeys(bool $remove = true)
     {
         $this->ignoreExtraKeys = true;
         $this->removeExtraKeys = $remove;
@@ -350,15 +346,13 @@ public function ignoreExtraKeys($remove = true)
     }
 
     /**
-     * Sets key normalization.
-     *
-     * @param bool $bool Whether to enable key normalization
+     * Sets whether to enable key normalization.
      *
      * @return $this
      */
-    public function normalizeKeys($bool)
+    public function normalizeKeys(bool $bool)
     {
-        $this->normalizeKeys = (bool) $bool;
+        $this->normalizeKeys = $bool;
 
         return $this;
     }
@@ -417,6 +411,10 @@ protected function createNode()
             }
 
             if ($this->default) {
+                if (!\is_array($this->defaultValue)) {
+                    throw new \InvalidArgumentException($node->getPath().': the default value of an array node has to be an array.');
+                }
+
                 $node->setDefaultValue($this->defaultValue);
             }
 
diff --git a/src/Symfony/Component/Config/Definition/Builder/ExprBuilder.php b/src/Symfony/Component/Config/Definition/Builder/ExprBuilder.php
index 05949d2b5a3b..4d918cef12b3 100644
--- a/src/Symfony/Component/Config/Definition/Builder/ExprBuilder.php
+++ b/src/Symfony/Component/Config/Definition/Builder/ExprBuilder.php
@@ -178,13 +178,11 @@ public function thenEmptyArray()
      *
      * if you want to add the value of the node in your message just use a %s placeholder.
      *
-     * @param string $message
-     *
      * @return $this
      *
      * @throws \InvalidArgumentException
      */
-    public function thenInvalid($message)
+    public function thenInvalid(string $message)
     {
         $this->thenPart = function ($v) use ($message) { throw new \InvalidArgumentException(sprintf($message, json_encode($v))); };
 
diff --git a/src/Symfony/Component/Config/Definition/Builder/MergeBuilder.php b/src/Symfony/Component/Config/Definition/Builder/MergeBuilder.php
index 105e2d64709b..a88d49ba93a4 100644
--- a/src/Symfony/Component/Config/Definition/Builder/MergeBuilder.php
+++ b/src/Symfony/Component/Config/Definition/Builder/MergeBuilder.php
@@ -30,11 +30,9 @@ public function __construct(NodeDefinition $node)
     /**
      * Sets whether the node can be unset.
      *
-     * @param bool $allow
-     *
      * @return $this
      */
-    public function allowUnset($allow = true)
+    public function allowUnset(bool $allow = true)
     {
         $this->allowFalse = $allow;
 
@@ -44,11 +42,9 @@ public function allowUnset($allow = true)
     /**
      * Sets whether the node can be overwritten.
      *
-     * @param bool $deny Whether the overwriting is forbidden or not
-     *
      * @return $this
      */
-    public function denyOverwrite($deny = true)
+    public function denyOverwrite(bool $deny = true)
     {
         $this->allowOverwrite = !$deny;
 
diff --git a/src/Symfony/Component/Config/Definition/Builder/NodeBuilder.php b/src/Symfony/Component/Config/Definition/Builder/NodeBuilder.php
index 84ad86794c1e..a9b48690e53c 100644
--- a/src/Symfony/Component/Config/Definition/Builder/NodeBuilder.php
+++ b/src/Symfony/Component/Config/Definition/Builder/NodeBuilder.php
@@ -49,11 +49,9 @@ public function setParent(ParentNodeDefinitionInterface $parent = null)
     /**
      * Creates a child array node.
      *
-     * @param string $name The name of the node
-     *
      * @return ArrayNodeDefinition The child node
      */
-    public function arrayNode($name)
+    public function arrayNode(string $name)
     {
         return $this->node($name, 'array');
     }
@@ -61,11 +59,9 @@ public function arrayNode($name)
     /**
      * Creates a child scalar node.
      *
-     * @param string $name The name of the node
-     *
      * @return ScalarNodeDefinition The child node
      */
-    public function scalarNode($name)
+    public function scalarNode(string $name)
     {
         return $this->node($name, 'scalar');
     }
@@ -73,11 +69,9 @@ public function scalarNode($name)
     /**
      * Creates a child Boolean node.
      *
-     * @param string $name The name of the node
-     *
      * @return BooleanNodeDefinition The child node
      */
-    public function booleanNode($name)
+    public function booleanNode(string $name)
     {
         return $this->node($name, 'boolean');
     }
@@ -85,11 +79,9 @@ public function booleanNode($name)
     /**
      * Creates a child integer node.
      *
-     * @param string $name The name of the node
-     *
      * @return IntegerNodeDefinition The child node
      */
-    public function integerNode($name)
+    public function integerNode(string $name)
     {
         return $this->node($name, 'integer');
     }
@@ -97,11 +89,9 @@ public function integerNode($name)
     /**
      * Creates a child float node.
      *
-     * @param string $name The name of the node
-     *
      * @return FloatNodeDefinition The child node
      */
-    public function floatNode($name)
+    public function floatNode(string $name)
     {
         return $this->node($name, 'float');
     }
@@ -109,11 +99,9 @@ public function floatNode($name)
     /**
      * Creates a child EnumNode.
      *
-     * @param string $name
-     *
      * @return EnumNodeDefinition
      */
-    public function enumNode($name)
+    public function enumNode(string $name)
     {
         return $this->node($name, 'enum');
     }
@@ -121,11 +109,9 @@ public function enumNode($name)
     /**
      * Creates a child variable node.
      *
-     * @param string $name The name of the node
-     *
      * @return VariableNodeDefinition The builder of the child node
      */
-    public function variableNode($name)
+    public function variableNode(string $name)
     {
         return $this->node($name, 'variable');
     }
@@ -143,15 +129,12 @@ public function end()
     /**
      * Creates a child node.
      *
-     * @param string|null $name The name of the node
-     * @param string      $type The type of the node
-     *
      * @return NodeDefinition The child node
      *
      * @throws \RuntimeException When the node type is not registered
      * @throws \RuntimeException When the node class is not found
      */
-    public function node($name, $type)
+    public function node(?string $name, string $type)
     {
         $class = $this->getNodeClass($type);
 
@@ -202,7 +185,7 @@ public function append(NodeDefinition $node)
      *
      * @return $this
      */
-    public function setNodeClass($type, $class)
+    public function setNodeClass(string $type, string $class)
     {
         $this->nodeMapping[strtolower($type)] = $class;
 
@@ -212,14 +195,12 @@ public function setNodeClass($type, $class)
     /**
      * Returns the class name of the node definition.
      *
-     * @param string $type The node type
-     *
      * @return string The node definition class name
      *
      * @throws \RuntimeException When the node type is not registered
      * @throws \RuntimeException When the node class is not found
      */
-    protected function getNodeClass($type)
+    protected function getNodeClass(string $type)
     {
         $type = strtolower($type);
 
diff --git a/src/Symfony/Component/Config/Definition/Builder/NodeDefinition.php b/src/Symfony/Component/Config/Definition/Builder/NodeDefinition.php
index c51b0b4a67ca..5e42b85e1f0b 100644
--- a/src/Symfony/Component/Config/Definition/Builder/NodeDefinition.php
+++ b/src/Symfony/Component/Config/Definition/Builder/NodeDefinition.php
@@ -59,11 +59,9 @@ public function setParent(NodeParentInterface $parent)
     /**
      * Sets info message.
      *
-     * @param string $info The info text
-     *
      * @return $this
      */
-    public function info($info)
+    public function info(string $info)
     {
         return $this->attribute('info', $info);
     }
@@ -83,12 +81,11 @@ public function example($example)
     /**
      * Sets an attribute on the node.
      *
-     * @param string $key
-     * @param mixed  $value
+     * @param mixed $value
      *
      * @return $this
      */
-    public function attribute($key, $value)
+    public function attribute(string $key, $value)
     {
         $this->attributes[$key] = $value;
 
@@ -112,7 +109,7 @@ public function end()
      *
      * @return NodeInterface
      */
-    public function getNode($forceRootNode = false)
+    public function getNode(bool $forceRootNode = false)
     {
         if ($forceRootNode) {
             $this->parent = null;
@@ -165,11 +162,9 @@ public function isRequired()
      * You can use %node% and %path% placeholders in your message to display,
      * respectively, the node name and its complete path.
      *
-     * @param string $message Deprecation message
-     *
      * @return $this
      */
-    public function setDeprecated($message = 'The child node "%node%" at path "%path%" is deprecated.')
+    public function setDeprecated(string $message = 'The child node "%node%" at path "%path%" is deprecated.')
     {
         $this->deprecationMessage = $message;
 
@@ -287,11 +282,9 @@ public function validate()
     /**
      * Sets whether the node can be overwritten.
      *
-     * @param bool $deny Whether the overwriting is forbidden or not
-     *
      * @return $this
      */
-    public function cannotBeOverwritten($deny = true)
+    public function cannotBeOverwritten(bool $deny = true)
     {
         $this->merge()->denyOverwrite($deny);
 
diff --git a/src/Symfony/Component/Config/Definition/Builder/NormalizationBuilder.php b/src/Symfony/Component/Config/Definition/Builder/NormalizationBuilder.php
index d3cdca90df1c..06cbbd4345ff 100644
--- a/src/Symfony/Component/Config/Definition/Builder/NormalizationBuilder.php
+++ b/src/Symfony/Component/Config/Definition/Builder/NormalizationBuilder.php
@@ -30,12 +30,12 @@ public function __construct(NodeDefinition $node)
     /**
      * Registers a key to remap to its plural form.
      *
-     * @param string $key    The key to remap
-     * @param string $plural The plural of the key in case of irregular plural
+     * @param string      $key    The key to remap
+     * @param string|null $plural The plural of the key in case of irregular plural
      *
      * @return $this
      */
-    public function remap($key, $plural = null)
+    public function remap(string $key, string $plural = null)
     {
         $this->remappings[] = [$key, null === $plural ? $key.'s' : $plural];
 
diff --git a/src/Symfony/Component/Config/Definition/Dumper/XmlReferenceDumper.php b/src/Symfony/Component/Config/Definition/Dumper/XmlReferenceDumper.php
index 7276b55a896c..5543f55879fc 100644
--- a/src/Symfony/Component/Config/Definition/Dumper/XmlReferenceDumper.php
+++ b/src/Symfony/Component/Config/Definition/Dumper/XmlReferenceDumper.php
@@ -26,7 +26,7 @@ class XmlReferenceDumper
 {
     private $reference;
 
-    public function dump(ConfigurationInterface $configuration, $namespace = null)
+    public function dump(ConfigurationInterface $configuration, string $namespace = null)
     {
         return $this->dumpNode($configuration->getConfigTreeBuilder()->buildTree(), $namespace);
     }
diff --git a/src/Symfony/Component/Config/Definition/PrototypeNodeInterface.php b/src/Symfony/Component/Config/Definition/PrototypeNodeInterface.php
index 53ed43667ffc..b160aa94a496 100644
--- a/src/Symfony/Component/Config/Definition/PrototypeNodeInterface.php
+++ b/src/Symfony/Component/Config/Definition/PrototypeNodeInterface.php
@@ -20,8 +20,6 @@ interface PrototypeNodeInterface extends NodeInterface
 {
     /**
      * Sets the name of the node.
-     *
-     * @param string $name The name of the node
      */
     public function setName(string $name);
 }
diff --git a/src/Symfony/Component/Config/Definition/PrototypedArrayNode.php b/src/Symfony/Component/Config/Definition/PrototypedArrayNode.php
index dd6ccd94a358..61291e2e057c 100644
--- a/src/Symfony/Component/Config/Definition/PrototypedArrayNode.php
+++ b/src/Symfony/Component/Config/Definition/PrototypedArrayNode.php
@@ -37,10 +37,8 @@ class PrototypedArrayNode extends ArrayNode
     /**
      * Sets the minimum number of elements that a prototype based node must
      * contain. By default this is zero, meaning no elements.
-     *
-     * @param int $number
      */
-    public function setMinNumberOfElements($number)
+    public function setMinNumberOfElements(int $number)
     {
         $this->minNumberOfElements = $number;
     }
@@ -69,7 +67,7 @@ public function setMinNumberOfElements($number)
      * @param string $attribute The name of the attribute which value is to be used as a key
      * @param bool   $remove    Whether or not to remove the key
      */
-    public function setKeyAttribute($attribute, $remove = true)
+    public function setKeyAttribute(string $attribute, bool $remove = true)
     {
         $this->keyAttribute = $attribute;
         $this->removeKeyAttribute = $remove;
@@ -87,17 +85,9 @@ public function getKeyAttribute()
 
     /**
      * Sets the default value of this node.
-     *
-     * @param string $value
-     *
-     * @throws \InvalidArgumentException if the default value is not an array
      */
-    public function setDefaultValue($value)
+    public function setDefaultValue(array $value)
     {
-        if (!\is_array($value)) {
-            throw new \InvalidArgumentException($this->getPath().': the default value of an array node has to be an array.');
-        }
-
         $this->defaultValue = $value;
     }
 
diff --git a/src/Symfony/Component/Config/FileLocator.php b/src/Symfony/Component/Config/FileLocator.php
index 345e63e6cd61..28a3559ee46b 100644
--- a/src/Symfony/Component/Config/FileLocator.php
+++ b/src/Symfony/Component/Config/FileLocator.php
@@ -76,12 +76,8 @@ public function locate(string $name, string $currentPath = null, $first = true)
 
     /**
      * Returns whether the file path is an absolute path.
-     *
-     * @param string $file A file path
-     *
-     * @return bool
      */
-    private function isAbsolutePath(string $file)
+    private function isAbsolutePath(string $file): bool
     {
         if ('/' === $file[0] || '\\' === $file[0]
             || (\strlen($file) > 3 && ctype_alpha($file[0])
diff --git a/src/Symfony/Component/Config/Loader/FileLoader.php b/src/Symfony/Component/Config/Loader/FileLoader.php
index ab48492a4b21..f39d08111905 100644
--- a/src/Symfony/Component/Config/Loader/FileLoader.php
+++ b/src/Symfony/Component/Config/Loader/FileLoader.php
@@ -38,10 +38,8 @@ public function __construct(FileLocatorInterface $locator)
 
     /**
      * Sets the current directory.
-     *
-     * @param string $dir
      */
-    public function setCurrentDir($dir)
+    public function setCurrentDir(string $dir)
     {
         $this->currentDir = $dir;
     }
@@ -70,7 +68,7 @@ public function getLocator()
      * @throws FileLoaderImportCircularReferenceException
      * @throws FileLocatorFileNotFoundException
      */
-    public function import($resource, $type = null, $ignoreErrors = false, $sourceResource = null)
+    public function import($resource, string $type = null, bool $ignoreErrors = false, string $sourceResource = null)
     {
         if (\is_string($resource) && \strlen($resource) !== $i = strcspn($resource, '*?{[')) {
             $ret = [];
@@ -125,7 +123,7 @@ protected function glob(string $pattern, bool $recursive, &$resource = null, boo
         yield from $resource;
     }
 
-    private function doImport($resource, $type = null, bool $ignoreErrors = false, $sourceResource = null)
+    private function doImport($resource, string $type = null, bool $ignoreErrors = false, string $sourceResource = null)
     {
         try {
             $loader = $this->resolve($resource, $type);
diff --git a/src/Symfony/Component/Config/Loader/Loader.php b/src/Symfony/Component/Config/Loader/Loader.php
index 698ab40afbf3..62cae685e298 100644
--- a/src/Symfony/Component/Config/Loader/Loader.php
+++ b/src/Symfony/Component/Config/Loader/Loader.php
@@ -46,7 +46,7 @@ public function setResolver(LoaderResolverInterface $resolver)
      *
      * @return mixed
      */
-    public function import($resource, $type = null)
+    public function import($resource, string $type = null)
     {
         return $this->resolve($resource, $type)->load($resource, $type);
     }
@@ -61,7 +61,7 @@ public function import($resource, $type = null)
      *
      * @throws LoaderLoadException If no loader is found
      */
-    public function resolve($resource, $type = null)
+    public function resolve($resource, string $type = null)
     {
         if ($this->supports($resource, $type)) {
             return $this;
diff --git a/src/Symfony/Component/Config/ResourceCheckerConfigCacheFactory.php b/src/Symfony/Component/Config/ResourceCheckerConfigCacheFactory.php
index fc1702f3cb89..a789644cae13 100644
--- a/src/Symfony/Component/Config/ResourceCheckerConfigCacheFactory.php
+++ b/src/Symfony/Component/Config/ResourceCheckerConfigCacheFactory.php
@@ -32,15 +32,11 @@ public function __construct(iterable $resourceCheckers = [])
     /**
      * {@inheritdoc}
      */
-    public function cache(string $file, $callback)
+    public function cache(string $file, callable $callable)
     {
-        if (!\is_callable($callback)) {
-            throw new \InvalidArgumentException(sprintf('Invalid type for callback argument. Expected callable, but got "%s".', \gettype($callback)));
-        }
-
         $cache = new ResourceCheckerConfigCache($file, $this->resourceCheckers);
         if (!$cache->isFresh()) {
-            $callback($cache);
+            $callable($cache);
         }
 
         return $cache;
diff --git a/src/Symfony/Component/Config/Tests/ConfigCacheFactoryTest.php b/src/Symfony/Component/Config/Tests/ConfigCacheFactoryTest.php
index 24e3224ce5ba..a1dd169eca0e 100644
--- a/src/Symfony/Component/Config/Tests/ConfigCacheFactoryTest.php
+++ b/src/Symfony/Component/Config/Tests/ConfigCacheFactoryTest.php
@@ -17,8 +17,7 @@
 class ConfigCacheFactoryTest extends TestCase
 {
     /**
-     * @expectedException \InvalidArgumentException
-     * @expectedExceptionMessage Invalid type for callback argument. Expected callable, but got "object".
+     * @expectedException \TypeError
      */
     public function testCacheWithInvalidCallback()
     {
diff --git a/src/Symfony/Component/Config/Tests/Fixtures/Builder/NodeBuilder.php b/src/Symfony/Component/Config/Tests/Fixtures/Builder/NodeBuilder.php
index 22b8b32fb6de..49209c9ba41d 100644
--- a/src/Symfony/Component/Config/Tests/Fixtures/Builder/NodeBuilder.php
+++ b/src/Symfony/Component/Config/Tests/Fixtures/Builder/NodeBuilder.php
@@ -20,7 +20,7 @@ public function barNode($name)
         return $this->node($name, 'bar');
     }
 
-    protected function getNodeClass($type)
+    protected function getNodeClass(string $type)
     {
         switch ($type) {
             case 'variable':
diff --git a/src/Symfony/Component/Config/Tests/Loader/FileLoaderTest.php b/src/Symfony/Component/Config/Tests/Loader/FileLoaderTest.php
index 0b2e3fb6b9a5..ad6d7271a868 100644
--- a/src/Symfony/Component/Config/Tests/Loader/FileLoaderTest.php
+++ b/src/Symfony/Component/Config/Tests/Loader/FileLoaderTest.php
@@ -98,12 +98,12 @@ class TestFileLoader extends FileLoader
 {
     private $supports = true;
 
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         return $resource;
     }
 
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return $this->supports;
     }
diff --git a/src/Symfony/Component/Config/Tests/Loader/LoaderTest.php b/src/Symfony/Component/Config/Tests/Loader/LoaderTest.php
index cd14d58fe5ea..9d43a2c4ef77 100644
--- a/src/Symfony/Component/Config/Tests/Loader/LoaderTest.php
+++ b/src/Symfony/Component/Config/Tests/Loader/LoaderTest.php
@@ -103,11 +103,11 @@ public function testImportWithType()
 
 class ProjectLoader1 extends Loader
 {
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
     }
 
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return \is_string($resource) && 'foo' === pathinfo($resource, PATHINFO_EXTENSION);
     }
diff --git a/src/Symfony/Component/Config/Util/XmlUtils.php b/src/Symfony/Component/Config/Util/XmlUtils.php
index cca11e7b92a3..60525faf1d8f 100644
--- a/src/Symfony/Component/Config/Util/XmlUtils.php
+++ b/src/Symfony/Component/Config/Util/XmlUtils.php
@@ -44,7 +44,7 @@ private function __construct()
      * @throws InvalidXmlException When parsing of XML with schema or callable produces any errors unrelated to the XML parsing itself
      * @throws \RuntimeException   When DOM extension is missing
      */
-    public static function parse($content, $schemaOrCallable = null)
+    public static function parse(string $content, $schemaOrCallable = null)
     {
         if (!\extension_loaded('dom')) {
             throw new \LogicException('Extension DOM is required.');
@@ -120,7 +120,7 @@ public static function parse($content, $schemaOrCallable = null)
      * @throws XmlParsingException       When XML parsing returns any errors
      * @throws \RuntimeException         When DOM extension is missing
      */
-    public static function loadFile($file, $schemaOrCallable = null)
+    public static function loadFile(string $file, $schemaOrCallable = null)
     {
         $content = @file_get_contents($file);
         if ('' === trim($content)) {
@@ -154,7 +154,7 @@ public static function loadFile($file, $schemaOrCallable = null)
      *
      * @return array A PHP array
      */
-    public static function convertDomElementToArray(\DOMElement $element, $checkPrefix = true)
+    public static function convertDomElementToArray(\DOMElement $element, bool $checkPrefix = true)
     {
         $prefix = (string) $element->prefix;
         $empty = true;
diff --git a/src/Symfony/Component/DependencyInjection/Config/ContainerParametersResourceChecker.php b/src/Symfony/Component/DependencyInjection/Config/ContainerParametersResourceChecker.php
index 6ed77e3fd2c4..2f2affaa5b6c 100644
--- a/src/Symfony/Component/DependencyInjection/Config/ContainerParametersResourceChecker.php
+++ b/src/Symfony/Component/DependencyInjection/Config/ContainerParametersResourceChecker.php
@@ -39,7 +39,7 @@ public function supports(ResourceInterface $metadata)
     /**
      * {@inheritdoc}
      */
-    public function isFresh(ResourceInterface $resource, $timestamp)
+    public function isFresh(ResourceInterface $resource, int $timestamp)
     {
         foreach ($resource->getParameters() as $key => $value) {
             if (!$this->container->hasParameter($key) || $this->container->getParameter($key) !== $value) {
diff --git a/src/Symfony/Component/DependencyInjection/Loader/ClosureLoader.php b/src/Symfony/Component/DependencyInjection/Loader/ClosureLoader.php
index 939dd7cb7c4a..57aa83d6a0a7 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/ClosureLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/ClosureLoader.php
@@ -33,7 +33,7 @@ public function __construct(ContainerBuilder $container)
     /**
      * {@inheritdoc}
      */
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         $resource($this->container);
     }
@@ -41,7 +41,7 @@ public function load($resource, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return $resource instanceof \Closure;
     }
diff --git a/src/Symfony/Component/DependencyInjection/Loader/DirectoryLoader.php b/src/Symfony/Component/DependencyInjection/Loader/DirectoryLoader.php
index a57cac3b5ee9..943986982e34 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/DirectoryLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/DirectoryLoader.php
@@ -21,7 +21,7 @@ class DirectoryLoader extends FileLoader
     /**
      * {@inheritdoc}
      */
-    public function load($file, $type = null)
+    public function load($file, string $type = null)
     {
         $file = rtrim($file, '/');
         $path = $this->locator->locate($file);
@@ -43,7 +43,7 @@ public function load($file, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         if ('directory' === $type) {
             return true;
diff --git a/src/Symfony/Component/DependencyInjection/Loader/GlobFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/GlobFileLoader.php
index 4b25610efe48..53af9cf2b8a1 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/GlobFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/GlobFileLoader.php
@@ -21,7 +21,7 @@ class GlobFileLoader extends FileLoader
     /**
      * {@inheritdoc}
      */
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         foreach ($this->glob($resource, false, $globResource) as $path => $info) {
             $this->import($path);
@@ -33,7 +33,7 @@ public function load($resource, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return 'glob' === $type;
     }
diff --git a/src/Symfony/Component/DependencyInjection/Loader/IniFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/IniFileLoader.php
index 307a3eefbbe5..7d4423477f41 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/IniFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/IniFileLoader.php
@@ -24,7 +24,7 @@ class IniFileLoader extends FileLoader
     /**
      * {@inheritdoc}
      */
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         $path = $this->locator->locate($resource);
 
@@ -49,7 +49,7 @@ public function load($resource, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string  $type = null)
     {
         if (!\is_string($resource)) {
             return false;
diff --git a/src/Symfony/Component/DependencyInjection/Loader/PhpFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/PhpFileLoader.php
index 033798f6813f..efc593f06b71 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/PhpFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/PhpFileLoader.php
@@ -51,7 +51,7 @@ public function load($resource, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         if (!\is_string($resource)) {
             return false;
diff --git a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
index 6368eb64c224..fd7a1fafc553 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
@@ -39,7 +39,7 @@ class XmlFileLoader extends FileLoader
     /**
      * {@inheritdoc}
      */
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         $path = $this->locator->locate($resource);
 
@@ -72,7 +72,7 @@ public function load($resource, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         if (!\is_string($resource)) {
             return false;
diff --git a/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
index f835fb5ce20c..336e0da5f25c 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
@@ -112,7 +112,7 @@ class YamlFileLoader extends FileLoader
     /**
      * {@inheritdoc}
      */
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         $path = $this->locator->locate($resource);
 
@@ -156,7 +156,7 @@ public function load($resource, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         if (!\is_string($resource)) {
             return false;
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Loader/FileLoaderTest.php b/src/Symfony/Component/DependencyInjection/Tests/Loader/FileLoaderTest.php
index b94ee1953fd7..ce9e4f0b9370 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Loader/FileLoaderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Loader/FileLoaderTest.php
@@ -235,12 +235,12 @@ public function testRegisterClassesWithIncompatibleExclude()
 
 class TestFileLoader extends FileLoader
 {
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         return $resource;
     }
 
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return false;
     }
diff --git a/src/Symfony/Component/DependencyInjection/composer.json b/src/Symfony/Component/DependencyInjection/composer.json
index 351471e26a3c..893722f19f05 100644
--- a/src/Symfony/Component/DependencyInjection/composer.json
+++ b/src/Symfony/Component/DependencyInjection/composer.json
@@ -22,7 +22,7 @@
     },
     "require-dev": {
         "symfony/yaml": "^4.4|^5.0",
-        "symfony/config": "^4.4|^5.0",
+        "symfony/config": "^5.0",
         "symfony/expression-language": "^4.4|^5.0"
     },
     "suggest": {
@@ -33,7 +33,7 @@
         "symfony/proxy-manager-bridge": "Generate service proxies to lazy load them"
     },
     "conflict": {
-        "symfony/config": "<4.4",
+        "symfony/config": "<5.0",
         "symfony/finder": "<4.4",
         "symfony/proxy-manager-bridge": "<4.4",
         "symfony/yaml": "<4.4"
diff --git a/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php b/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
index d6dc923674e6..a654aef58247 100644
--- a/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
+++ b/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
@@ -94,7 +94,7 @@ public function setRouteAnnotationClass($class)
      *
      * @throws \InvalidArgumentException When route can't be parsed
      */
-    public function load($class, $type = null)
+    public function load($class, string $type = null)
     {
         if (!class_exists($class)) {
             throw new \InvalidArgumentException(sprintf('Class "%s" does not exist.', $class));
diff --git a/src/Symfony/Component/Routing/Loader/AnnotationDirectoryLoader.php b/src/Symfony/Component/Routing/Loader/AnnotationDirectoryLoader.php
index 3fb70ea20b43..7e52f3196fb3 100644
--- a/src/Symfony/Component/Routing/Loader/AnnotationDirectoryLoader.php
+++ b/src/Symfony/Component/Routing/Loader/AnnotationDirectoryLoader.php
@@ -32,7 +32,7 @@ class AnnotationDirectoryLoader extends AnnotationFileLoader
      *
      * @throws \InvalidArgumentException When the directory does not exist or its routes cannot be parsed
      */
-    public function load($path, $type = null)
+    public function load($path, string $type = null)
     {
         if (!is_dir($dir = $this->locator->locate($path))) {
             return parent::supports($path, $type) ? parent::load($path, $type) : new RouteCollection();
@@ -74,7 +74,7 @@ function (\SplFileInfo $current) {
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         if ('annotation' === $type) {
             return true;
diff --git a/src/Symfony/Component/Routing/Loader/AnnotationFileLoader.php b/src/Symfony/Component/Routing/Loader/AnnotationFileLoader.php
index a0965749696a..264ec28a0148 100644
--- a/src/Symfony/Component/Routing/Loader/AnnotationFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/AnnotationFileLoader.php
@@ -50,7 +50,7 @@ public function __construct(FileLocatorInterface $locator, AnnotationClassLoader
      *
      * @throws \InvalidArgumentException When the file does not exist or its routes cannot be parsed
      */
-    public function load($file, $type = null)
+    public function load($file, string $type = null)
     {
         $path = $this->locator->locate($file);
 
@@ -73,7 +73,7 @@ public function load($file, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return \is_string($resource) && 'php' === pathinfo($resource, PATHINFO_EXTENSION) && (!$type || 'annotation' === $type);
     }
diff --git a/src/Symfony/Component/Routing/Loader/ClosureLoader.php b/src/Symfony/Component/Routing/Loader/ClosureLoader.php
index 5df9f6ae8f17..cea5f9c1947d 100644
--- a/src/Symfony/Component/Routing/Loader/ClosureLoader.php
+++ b/src/Symfony/Component/Routing/Loader/ClosureLoader.php
@@ -31,7 +31,7 @@ class ClosureLoader extends Loader
      *
      * @return RouteCollection A RouteCollection instance
      */
-    public function load($closure, $type = null)
+    public function load($closure, string $type = null)
     {
         return $closure();
     }
@@ -39,7 +39,7 @@ public function load($closure, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return $resource instanceof \Closure && (!$type || 'closure' === $type);
     }
diff --git a/src/Symfony/Component/Routing/Loader/DirectoryLoader.php b/src/Symfony/Component/Routing/Loader/DirectoryLoader.php
index 08e833e0a1ea..c0f349177475 100644
--- a/src/Symfony/Component/Routing/Loader/DirectoryLoader.php
+++ b/src/Symfony/Component/Routing/Loader/DirectoryLoader.php
@@ -20,7 +20,7 @@ class DirectoryLoader extends FileLoader
     /**
      * {@inheritdoc}
      */
-    public function load($file, $type = null)
+    public function load($file, string $type = null)
     {
         $path = $this->locator->locate($file);
 
@@ -49,7 +49,7 @@ public function load($file, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         // only when type is forced to directory, not to conflict with AnnotationLoader
 
diff --git a/src/Symfony/Component/Routing/Loader/GlobFileLoader.php b/src/Symfony/Component/Routing/Loader/GlobFileLoader.php
index 03ee341b9825..780fb15dc779 100644
--- a/src/Symfony/Component/Routing/Loader/GlobFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/GlobFileLoader.php
@@ -24,7 +24,7 @@ class GlobFileLoader extends FileLoader
     /**
      * {@inheritdoc}
      */
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         $collection = new RouteCollection();
 
@@ -40,7 +40,7 @@ public function load($resource, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return 'glob' === $type;
     }
diff --git a/src/Symfony/Component/Routing/Loader/ObjectRouteLoader.php b/src/Symfony/Component/Routing/Loader/ObjectRouteLoader.php
index 2486536b25a6..d16a8bb218b3 100644
--- a/src/Symfony/Component/Routing/Loader/ObjectRouteLoader.php
+++ b/src/Symfony/Component/Routing/Loader/ObjectRouteLoader.php
@@ -42,7 +42,7 @@ abstract protected function getServiceObject($id);
      *
      * @return RouteCollection
      */
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         if (!preg_match('/^[^\:]+(?:::?(?:[^\:]+))?$/', $resource)) {
             throw new \InvalidArgumentException(sprintf('Invalid resource "%s" passed to the "service" route loader: use the format "service::method" or "service" if your service has an "__invoke" method.', $resource));
@@ -79,7 +79,7 @@ public function load($resource, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return 'service' === $type;
     }
diff --git a/src/Symfony/Component/Routing/Loader/PhpFileLoader.php b/src/Symfony/Component/Routing/Loader/PhpFileLoader.php
index 1d1ae7dfcb84..7af543744eba 100644
--- a/src/Symfony/Component/Routing/Loader/PhpFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/PhpFileLoader.php
@@ -33,7 +33,7 @@ class PhpFileLoader extends FileLoader
      *
      * @return RouteCollection A RouteCollection instance
      */
-    public function load($file, $type = null)
+    public function load($file, string $type = null)
     {
         $path = $this->locator->locate($file);
         $this->setCurrentDir(\dirname($path));
@@ -61,7 +61,7 @@ public function load($file, $type = null)
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return \is_string($resource) && 'php' === pathinfo($resource, PATHINFO_EXTENSION) && (!$type || 'php' === $type);
     }
diff --git a/src/Symfony/Component/Routing/Loader/XmlFileLoader.php b/src/Symfony/Component/Routing/Loader/XmlFileLoader.php
index 7a2cbb94b48f..d619be04d13d 100644
--- a/src/Symfony/Component/Routing/Loader/XmlFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/XmlFileLoader.php
@@ -39,7 +39,7 @@ class XmlFileLoader extends FileLoader
      * @throws \InvalidArgumentException when the file cannot be loaded or when the XML cannot be
      *                                   parsed because it does not validate against the scheme
      */
-    public function load($file, $type = null)
+    public function load($file, string $type = null)
     {
         $path = $this->locator->locate($file);
 
@@ -91,7 +91,7 @@ protected function parseNode(RouteCollection $collection, \DOMElement $node, $pa
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return \is_string($resource) && 'xml' === pathinfo($resource, PATHINFO_EXTENSION) && (!$type || 'xml' === $type);
     }
diff --git a/src/Symfony/Component/Routing/Loader/YamlFileLoader.php b/src/Symfony/Component/Routing/Loader/YamlFileLoader.php
index 6f2d04965a0c..f044418652e8 100644
--- a/src/Symfony/Component/Routing/Loader/YamlFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/YamlFileLoader.php
@@ -42,7 +42,7 @@ class YamlFileLoader extends FileLoader
      *
      * @throws \InvalidArgumentException When a route can't be parsed because YAML is invalid
      */
-    public function load($file, $type = null)
+    public function load($file, string $type = null)
     {
         $path = $this->locator->locate($file);
 
diff --git a/src/Symfony/Component/Routing/composer.json b/src/Symfony/Component/Routing/composer.json
index eb39683d43b7..9cb239e4a505 100644
--- a/src/Symfony/Component/Routing/composer.json
+++ b/src/Symfony/Component/Routing/composer.json
@@ -19,7 +19,7 @@
         "php": "^7.2.9"
     },
     "require-dev": {
-        "symfony/config": "^4.4|^5.0",
+        "symfony/config": "^5.0",
         "symfony/http-foundation": "^4.4|^5.0",
         "symfony/yaml": "^4.4|^5.0",
         "symfony/expression-language": "^4.4|^5.0",
@@ -28,7 +28,7 @@
         "psr/log": "~1.0"
     },
     "conflict": {
-        "symfony/config": "<4.4",
+        "symfony/config": "<5.0",
         "symfony/dependency-injection": "<4.4",
         "symfony/yaml": "<4.4"
     },