diff --git a/src/Symfony/Component/HttpFoundation/AcceptHeader.php b/src/Symfony/Component/HttpFoundation/AcceptHeader.php
index 3f5fbb8f3b..bbbd62a6d2 100644
--- a/src/Symfony/Component/HttpFoundation/AcceptHeader.php
+++ b/src/Symfony/Component/HttpFoundation/AcceptHeader.php
@@ -153,7 +153,7 @@ class AcceptHeader
     /**
      * Sorts items by descending quality.
      */
-    private function sort()
+    private function sort(): void
     {
         if (!$this->sorted) {
             uasort($this->items, function (AcceptHeaderItem $a, AcceptHeaderItem $b) {
diff --git a/src/Symfony/Component/HttpFoundation/BinaryFileResponse.php b/src/Symfony/Component/HttpFoundation/BinaryFileResponse.php
index 79329e2e2b..4fd4aec1af 100644
--- a/src/Symfony/Component/HttpFoundation/BinaryFileResponse.php
+++ b/src/Symfony/Component/HttpFoundation/BinaryFileResponse.php
@@ -269,7 +269,7 @@ class BinaryFileResponse extends Response
         return $this;
     }
 
-    private function hasValidIfRangeHeader(?string $header)
+    private function hasValidIfRangeHeader(?string $header): bool
     {
         if ($this->getEtag() === $header) {
             return true;
diff --git a/src/Symfony/Component/HttpFoundation/File/Exception/AccessDeniedException.php b/src/Symfony/Component/HttpFoundation/File/Exception/AccessDeniedException.php
index c25c3629bb..136d2a9f51 100644
--- a/src/Symfony/Component/HttpFoundation/File/Exception/AccessDeniedException.php
+++ b/src/Symfony/Component/HttpFoundation/File/Exception/AccessDeniedException.php
@@ -18,9 +18,6 @@ namespace Symfony\Component\HttpFoundation\File\Exception;
  */
 class AccessDeniedException extends FileException
 {
-    /**
-     * @param string $path The path to the accessed file
-     */
     public function __construct(string $path)
     {
         parent::__construct(sprintf('The file %s could not be accessed', $path));
diff --git a/src/Symfony/Component/HttpFoundation/File/Exception/FileNotFoundException.php b/src/Symfony/Component/HttpFoundation/File/Exception/FileNotFoundException.php
index 0f1f3f951d..31bdf68fef 100644
--- a/src/Symfony/Component/HttpFoundation/File/Exception/FileNotFoundException.php
+++ b/src/Symfony/Component/HttpFoundation/File/Exception/FileNotFoundException.php
@@ -18,9 +18,6 @@ namespace Symfony\Component\HttpFoundation\File\Exception;
  */
 class FileNotFoundException extends FileException
 {
-    /**
-     * @param string $path The path to the file that was not found
-     */
     public function __construct(string $path)
     {
         parent::__construct(sprintf('The file "%s" does not exist', $path));
diff --git a/src/Symfony/Component/HttpFoundation/File/File.php b/src/Symfony/Component/HttpFoundation/File/File.php
index 396ff3450e..4906588a72 100644
--- a/src/Symfony/Component/HttpFoundation/File/File.php
+++ b/src/Symfony/Component/HttpFoundation/File/File.php
@@ -99,6 +99,9 @@ class File extends \SplFileInfo
         return $target;
     }
 
+    /**
+     * @return self
+     */
     protected function getTargetFile($directory, $name = null)
     {
         if (!is_dir($directory)) {
@@ -119,7 +122,7 @@ class File extends \SplFileInfo
      *
      * @param string $name The new file name
      *
-     * @return string containing
+     * @return string
      */
     protected function getName($name)
     {
diff --git a/src/Symfony/Component/HttpFoundation/FileBag.php b/src/Symfony/Component/HttpFoundation/FileBag.php
index efd83ffeb8..eec3ff4465 100644
--- a/src/Symfony/Component/HttpFoundation/FileBag.php
+++ b/src/Symfony/Component/HttpFoundation/FileBag.php
@@ -24,7 +24,7 @@ class FileBag extends ParameterBag
     private static $fileKeys = ['error', 'name', 'size', 'tmp_name', 'type'];
 
     /**
-     * @param array $parameters An array of HTTP files
+     * @param array|UploadedFile[] $parameters An array of HTTP files
      */
     public function __construct(array $parameters = [])
     {
diff --git a/src/Symfony/Component/HttpFoundation/HeaderBag.php b/src/Symfony/Component/HttpFoundation/HeaderBag.php
index ef549f3c36..3d12cb0f66 100644
--- a/src/Symfony/Component/HttpFoundation/HeaderBag.php
+++ b/src/Symfony/Component/HttpFoundation/HeaderBag.php
@@ -21,9 +21,6 @@ class HeaderBag implements \IteratorAggregate, \Countable
     protected $headers = [];
     protected $cacheControl = [];
 
-    /**
-     * @param array $headers An array of HTTP headers
-     */
     public function __construct(array $headers = [])
     {
         foreach ($headers as $key => $values) {
@@ -85,8 +82,6 @@ class HeaderBag implements \IteratorAggregate, \Countable
 
     /**
      * Replaces the current HTTP headers by a new set.
-     *
-     * @param array $headers An array of HTTP headers
      */
     public function replace(array $headers = [])
     {
@@ -96,8 +91,6 @@ class HeaderBag implements \IteratorAggregate, \Countable
 
     /**
      * Adds new headers the current HTTP headers set.
-     *
-     * @param array $headers An array of HTTP headers
      */
     public function add(array $headers)
     {
@@ -204,10 +197,9 @@ class HeaderBag implements \IteratorAggregate, \Countable
     /**
      * Returns the HTTP header value converted to a date.
      *
-     * @param string    $key     The parameter key
-     * @param \DateTime $default The default value
+     * @param string $key The parameter key
      *
-     * @return \DateTime|null The parsed DateTime or the default value if the header does not exist
+     * @return \DateTimeInterface|null The parsed DateTime or the default value if the header does not exist
      *
      * @throws \RuntimeException When the HTTP header is not parseable
      */
diff --git a/src/Symfony/Component/HttpFoundation/ParameterBag.php b/src/Symfony/Component/HttpFoundation/ParameterBag.php
index 194ba2c6c5..20ca6758b6 100644
--- a/src/Symfony/Component/HttpFoundation/ParameterBag.php
+++ b/src/Symfony/Component/HttpFoundation/ParameterBag.php
@@ -23,9 +23,6 @@ class ParameterBag implements \IteratorAggregate, \Countable
      */
     protected $parameters;
 
-    /**
-     * @param array $parameters An array of parameters
-     */
     public function __construct(array $parameters = [])
     {
         $this->parameters = $parameters;
@@ -53,8 +50,6 @@ class ParameterBag implements \IteratorAggregate, \Countable
 
     /**
      * Replaces the current parameters by a new set.
-     *
-     * @param array $parameters An array of parameters
      */
     public function replace(array $parameters = [])
     {
@@ -63,8 +58,6 @@ class ParameterBag implements \IteratorAggregate, \Countable
 
     /**
      * Adds parameters.
-     *
-     * @param array $parameters An array of parameters
      */
     public function add(array $parameters = [])
     {
diff --git a/src/Symfony/Component/HttpFoundation/Request.php b/src/Symfony/Component/HttpFoundation/Request.php
index 2edc349103..2a980bfa50 100644
--- a/src/Symfony/Component/HttpFoundation/Request.php
+++ b/src/Symfony/Component/HttpFoundation/Request.php
@@ -632,7 +632,7 @@ class Request
      */
     public static function normalizeQueryString($qs)
     {
-        if ('' == $qs) {
+        if ('' === ($qs ?? '')) {
             return '';
         }
 
@@ -702,7 +702,7 @@ class Request
     /**
      * Gets the Session.
      *
-     * @return SessionInterface|null The session
+     * @return SessionInterface The session
      */
     public function getSession()
     {
@@ -1591,7 +1591,7 @@ class Request
     /**
      * Returns the preferred language.
      *
-     * @param array $locales An array of ordered available locales
+     * @param string[] $locales An array of ordered available locales
      *
      * @return string|null The preferred locale
      */
@@ -1920,7 +1920,7 @@ class Request
         ];
     }
 
-    private function setPhpDefaultLocale(string $locale)
+    private function setPhpDefaultLocale(string $locale): void
     {
         // if either the class Locale doesn't exist, or an exception is thrown when
         // setting the default locale, the intl module is not installed, and
@@ -1982,7 +1982,7 @@ class Request
         return self::$trustedProxies && IpUtils::checkIp($this->server->get('REMOTE_ADDR'), self::$trustedProxies);
     }
 
-    private function getTrustedValues(int $type, string $ip = null)
+    private function getTrustedValues(int $type, string $ip = null): array
     {
         $clientValues = [];
         $forwardedValues = [];
@@ -2033,7 +2033,7 @@ class Request
         throw new ConflictingHeadersException(sprintf('The request has both a trusted "%s" header and a trusted "%s" header, conflicting with each other. You should either configure your proxy to remove one of them, or configure your project to distrust the offending one.', self::$trustedHeaders[self::HEADER_FORWARDED], self::$trustedHeaders[$type]));
     }
 
-    private function normalizeAndFilterClientIps(array $clientIps, string $ip)
+    private function normalizeAndFilterClientIps(array $clientIps, string $ip): array
     {
         if (!$clientIps) {
             return [];
diff --git a/src/Symfony/Component/HttpFoundation/RequestMatcher.php b/src/Symfony/Component/HttpFoundation/RequestMatcher.php
index d79c7f2ea2..ca90f8b1f9 100644
--- a/src/Symfony/Component/HttpFoundation/RequestMatcher.php
+++ b/src/Symfony/Component/HttpFoundation/RequestMatcher.php
@@ -54,11 +54,8 @@ class RequestMatcher implements RequestMatcherInterface
     private $schemes = [];
 
     /**
-     * @param string|null          $path
-     * @param string|null          $host
      * @param string|string[]|null $methods
      * @param string|string[]|null $ips
-     * @param array                $attributes
      * @param string|string[]|null $schemes
      */
     public function __construct(string $path = null, string $host = null, $methods = null, $ips = null, array $attributes = [], $schemes = null, int $port = null)
diff --git a/src/Symfony/Component/HttpFoundation/Response.php b/src/Symfony/Component/HttpFoundation/Response.php
index c6a3b32ddc..15e1e1bba2 100644
--- a/src/Symfony/Component/HttpFoundation/Response.php
+++ b/src/Symfony/Component/HttpFoundation/Response.php
@@ -1208,7 +1208,7 @@ class Response
      *
      * @final
      */
-    public static function closeOutputBuffers(int $targetLevel, bool $flush)
+    public static function closeOutputBuffers(int $targetLevel, bool $flush): void
     {
         $status = ob_get_status(true);
         $level = \count($status);
@@ -1230,7 +1230,7 @@ class Response
      *
      * @final
      */
-    protected function ensureIEOverSSLCompatibility(Request $request)
+    protected function ensureIEOverSSLCompatibility(Request $request): void
     {
         if (false !== stripos($this->headers->get('Content-Disposition'), 'attachment') && 1 == preg_match('/MSIE (.*?);/i', $request->server->get('HTTP_USER_AGENT'), $match) && true === $request->isSecure()) {
             if ((int) preg_replace('/(MSIE )(.*?);/', '$2', $match[0]) < 9) {
diff --git a/src/Symfony/Component/HttpFoundation/ResponseHeaderBag.php b/src/Symfony/Component/HttpFoundation/ResponseHeaderBag.php
index 0cfc6f6ac8..79f58eb866 100644
--- a/src/Symfony/Component/HttpFoundation/ResponseHeaderBag.php
+++ b/src/Symfony/Component/HttpFoundation/ResponseHeaderBag.php
@@ -298,7 +298,7 @@ class ResponseHeaderBag extends HeaderBag
         return $header;
     }
 
-    private function initDate()
+    private function initDate(): void
     {
         $now = \DateTime::createFromFormat('U', time());
         $now->setTimezone(new \DateTimeZone('UTC'));
diff --git a/src/Symfony/Component/HttpFoundation/Session/Attribute/AttributeBagInterface.php b/src/Symfony/Component/HttpFoundation/Session/Attribute/AttributeBagInterface.php
index 0d8d17991b..6fa2293970 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Attribute/AttributeBagInterface.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Attribute/AttributeBagInterface.php
@@ -50,15 +50,10 @@ interface AttributeBagInterface extends SessionBagInterface
     /**
      * Returns attributes.
      *
-     * @return array Attributes
+     * @return array
      */
     public function all();
 
-    /**
-     * Sets attributes.
-     *
-     * @param array $attributes Attributes
-     */
     public function replace(array $attributes);
 
     /**
diff --git a/src/Symfony/Component/HttpFoundation/Session/Session.php b/src/Symfony/Component/HttpFoundation/Session/Session.php
index eb1dc2af97..365ef29cf0 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Session.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Session.php
@@ -129,7 +129,7 @@ class Session implements SessionInterface, \IteratorAggregate, \Countable
     /**
      * Returns the number of attributes.
      *
-     * @return int The number of attributes
+     * @return int
      */
     public function count()
     {
diff --git a/src/Symfony/Component/HttpFoundation/Session/SessionBagProxy.php b/src/Symfony/Component/HttpFoundation/Session/SessionBagProxy.php
index 3504bdfe7b..2ea1cd5a5d 100644
--- a/src/Symfony/Component/HttpFoundation/Session/SessionBagProxy.php
+++ b/src/Symfony/Component/HttpFoundation/Session/SessionBagProxy.php
@@ -63,7 +63,7 @@ final class SessionBagProxy implements SessionBagInterface
     /**
      * {@inheritdoc}
      */
-    public function initialize(array &$array)
+    public function initialize(array &$array): void
     {
         ++$this->usageIndex;
         $this->data[$this->bag->getStorageKey()] = &$array;
diff --git a/src/Symfony/Component/HttpFoundation/Session/SessionInterface.php b/src/Symfony/Component/HttpFoundation/Session/SessionInterface.php
index 95fca857e2..e758c6bda6 100644
--- a/src/Symfony/Component/HttpFoundation/Session/SessionInterface.php
+++ b/src/Symfony/Component/HttpFoundation/Session/SessionInterface.php
@@ -23,7 +23,7 @@ interface SessionInterface
     /**
      * Starts the session storage.
      *
-     * @return bool True if session started
+     * @return bool
      *
      * @throws \RuntimeException if session fails to start
      */
@@ -32,7 +32,7 @@ interface SessionInterface
     /**
      * Returns the session ID.
      *
-     * @return string The session ID
+     * @return string
      */
     public function getId();
 
@@ -46,7 +46,7 @@ interface SessionInterface
     /**
      * Returns the session name.
      *
-     * @return mixed The session name
+     * @return string
      */
     public function getName();
 
@@ -68,7 +68,7 @@ interface SessionInterface
      *                      to expire with browser session. Time is in seconds, and is
      *                      not a Unix timestamp.
      *
-     * @return bool True if session invalidated, false if error
+     * @return bool
      */
     public function invalidate($lifetime = null);
 
@@ -82,7 +82,7 @@ interface SessionInterface
      *                       to expire with browser session. Time is in seconds, and is
      *                       not a Unix timestamp.
      *
-     * @return bool True if session migrated, false if error
+     * @return bool
      */
     public function migrate($destroy = false, $lifetime = null);
 
@@ -100,7 +100,7 @@ interface SessionInterface
      *
      * @param string $name The attribute name
      *
-     * @return bool true if the attribute is defined, false otherwise
+     * @return bool
      */
     public function has($name);
 
@@ -125,14 +125,12 @@ interface SessionInterface
     /**
      * Returns attributes.
      *
-     * @return array Attributes
+     * @return array
      */
     public function all();
 
     /**
      * Sets attributes.
-     *
-     * @param array $attributes Attributes
      */
     public function replace(array $attributes);
 
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/MemcachedSessionHandler.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/MemcachedSessionHandler.php
index f1bce4a352..3faa336f69 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/MemcachedSessionHandler.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/MemcachedSessionHandler.php
@@ -40,8 +40,6 @@ class MemcachedSessionHandler extends AbstractSessionHandler
      *  * prefix: The prefix to use for the memcached keys in order to avoid collision
      *  * expiretime: The time to live in seconds.
      *
-     * @param \Memcached $memcached A \Memcached instance
-     *
      * @throws \InvalidArgumentException When unsupported options are passed
      */
     public function __construct(\Memcached $memcached, array $options = [])
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
index 666d7e464d..f1648adaa5 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
@@ -423,7 +423,7 @@ class PdoSessionHandler extends AbstractSessionHandler
     /**
      * Lazy-connects to the database.
      */
-    private function connect(string $dsn)
+    private function connect(string $dsn): void
     {
         $this->pdo = new \PDO($dsn, $this->username, $this->password, $this->connectionOptions);
         $this->pdo->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
@@ -534,7 +534,7 @@ class PdoSessionHandler extends AbstractSessionHandler
      * due to https://percona.com/blog/2013/12/12/one-more-innodb-gap-lock-to-avoid/ .
      * So we change it to READ COMMITTED.
      */
-    private function beginTransaction()
+    private function beginTransaction(): void
     {
         if (!$this->inTransaction) {
             if ('sqlite' === $this->driver) {
@@ -552,7 +552,7 @@ class PdoSessionHandler extends AbstractSessionHandler
     /**
      * Helper method to commit a transaction.
      */
-    private function commit()
+    private function commit(): void
     {
         if ($this->inTransaction) {
             try {
@@ -574,7 +574,7 @@ class PdoSessionHandler extends AbstractSessionHandler
     /**
      * Helper method to rollback a transaction.
      */
-    private function rollback()
+    private function rollback(): void
     {
         // We only need to rollback if we are in a transaction. Otherwise the resulting
         // error would hide the real problem why rollback was called. We might not be
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/MetadataBag.php b/src/Symfony/Component/HttpFoundation/Session/Storage/MetadataBag.php
index ece3ff34f5..5fe40fc106 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/MetadataBag.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/MetadataBag.php
@@ -159,7 +159,7 @@ class MetadataBag implements SessionBagInterface
         $this->name = $name;
     }
 
-    private function stampCreated(int $lifetime = null)
+    private function stampCreated(int $lifetime = null): void
     {
         $timeStamp = time();
         $this->meta[self::CREATED] = $this->meta[self::UPDATED] = $this->lastUsed = $timeStamp;
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/MockFileSessionStorage.php b/src/Symfony/Component/HttpFoundation/Session/Storage/MockFileSessionStorage.php
index 7916fa8191..02fe4dad48 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/MockFileSessionStorage.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/MockFileSessionStorage.php
@@ -121,7 +121,7 @@ class MockFileSessionStorage extends MockArraySessionStorage
      * Deletes a session from persistent storage.
      * Deliberately leaves session data in memory intact.
      */
-    private function destroy()
+    private function destroy(): void
     {
         if (is_file($this->getFilePath())) {
             unlink($this->getFilePath());
@@ -139,7 +139,7 @@ class MockFileSessionStorage extends MockArraySessionStorage
     /**
      * Reads session from storage and loads session.
      */
-    private function read()
+    private function read(): void
     {
         $filePath = $this->getFilePath();
         $this->data = is_readable($filePath) && is_file($filePath) ? unserialize(file_get_contents($filePath)) : [];
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php b/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
index 7e177ca50b..2a57e6ce88 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
@@ -97,7 +97,7 @@ class NativeSessionStorage implements SessionStorageInterface
      * trans_sid_hosts, $_SERVER['HTTP_HOST']
      * trans_sid_tags, "a=href,area=href,frame=src,form="
      *
-     * @param \SessionHandlerInterface|null $handler
+     * @param AbstractProxy|\SessionHandlerInterface|null $handler
      */
     public function __construct(array $options = [], $handler = null, MetadataBag $metaBag = null)
     {
@@ -409,7 +409,7 @@ class NativeSessionStorage implements SessionStorageInterface
      * @see https://php.net/sessionhandler
      * @see https://github.com/zikula/NativeSession
      *
-     * @param \SessionHandlerInterface|null $saveHandler
+     * @param AbstractProxy|\SessionHandlerInterface|null $saveHandler
      *
      * @throws \InvalidArgumentException
      */
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/PhpBridgeSessionStorage.php b/src/Symfony/Component/HttpFoundation/Session/Storage/PhpBridgeSessionStorage.php
index f0fac5843a..72dbef1346 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/PhpBridgeSessionStorage.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/PhpBridgeSessionStorage.php
@@ -11,6 +11,8 @@
 
 namespace Symfony\Component\HttpFoundation\Session\Storage;
 
+use Symfony\Component\HttpFoundation\Session\Storage\Proxy\AbstractProxy;
+
 /**
  * Allows session to be started by PHP and managed by Symfony.
  *
@@ -19,7 +21,7 @@ namespace Symfony\Component\HttpFoundation\Session\Storage;
 class PhpBridgeSessionStorage extends NativeSessionStorage
 {
     /**
-     * @param \SessionHandlerInterface|null $handler
+     * @param AbstractProxy|\SessionHandlerInterface|null $handler
      */
     public function __construct($handler = null, MetadataBag $metaBag = null)
     {
diff --git a/src/Symfony/Component/HttpFoundation/StreamedResponse.php b/src/Symfony/Component/HttpFoundation/StreamedResponse.php
index 8310ea72d6..06d7a47ad8 100644
--- a/src/Symfony/Component/HttpFoundation/StreamedResponse.php
+++ b/src/Symfony/Component/HttpFoundation/StreamedResponse.php
@@ -63,8 +63,6 @@ class StreamedResponse extends Response
     /**
      * Sets the PHP callback associated with this Response.
      *
-     * @param callable $callback A valid PHP callback
-     *
      * @return $this
      */
     public function setCallback(callable $callback)