diff --git a/src/Symfony/Component/HttpFoundation/BinaryFileResponse.php b/src/Symfony/Component/HttpFoundation/BinaryFileResponse.php
index 6c9a995e9a..f43114111b 100644
--- a/src/Symfony/Component/HttpFoundation/BinaryFileResponse.php
+++ b/src/Symfony/Component/HttpFoundation/BinaryFileResponse.php
@@ -327,12 +327,12 @@ class BinaryFileResponse extends Response
         if (null !== $content) {
             throw new \LogicException('The content cannot be set on a BinaryFileResponse instance.');
         }
+
+        return $this;
     }
 
     /**
      * {@inheritdoc}
-     *
-     * @return false
      */
     public function getContent()
     {
diff --git a/src/Symfony/Component/HttpFoundation/FileBag.php b/src/Symfony/Component/HttpFoundation/FileBag.php
index ca849b3d7b..024fadf203 100644
--- a/src/Symfony/Component/HttpFoundation/FileBag.php
+++ b/src/Symfony/Component/HttpFoundation/FileBag.php
@@ -75,8 +75,8 @@ class FileBag extends ParameterBag
             return $file;
         }
 
-        $file = $this->fixPhpFilesArray($file);
         if (\is_array($file)) {
+            $file = $this->fixPhpFilesArray($file);
             $keys = array_keys($file);
             sort($keys);
 
@@ -109,14 +109,12 @@ class FileBag extends ParameterBag
      * It's safe to pass an already converted array, in which case this method
      * just returns the original array unmodified.
      *
+     * @param array $data
+     *
      * @return array
      */
     protected function fixPhpFilesArray($data)
     {
-        if (!\is_array($data)) {
-            return $data;
-        }
-
         $keys = array_keys($data);
         sort($keys);
 
diff --git a/src/Symfony/Component/HttpFoundation/HeaderBag.php b/src/Symfony/Component/HttpFoundation/HeaderBag.php
index 9798173e64..08299977ca 100644
--- a/src/Symfony/Component/HttpFoundation/HeaderBag.php
+++ b/src/Symfony/Component/HttpFoundation/HeaderBag.php
@@ -121,7 +121,7 @@ class HeaderBag implements \IteratorAggregate, \Countable
         }
 
         if ($first) {
-            return \count($headers[$key]) ? $headers[$key][0] : $default;
+            return \count($headers[$key]) ? (string) $headers[$key][0] : $default;
         }
 
         return $headers[$key];
diff --git a/src/Symfony/Component/HttpFoundation/Request.php b/src/Symfony/Component/HttpFoundation/Request.php
index 3b9bf2f49e..3fc7b71e6e 100644
--- a/src/Symfony/Component/HttpFoundation/Request.php
+++ b/src/Symfony/Component/HttpFoundation/Request.php
@@ -528,6 +528,10 @@ class Request
         try {
             $content = $this->getContent();
         } catch (\LogicException $e) {
+            if (\PHP_VERSION_ID >= 70400) {
+                throw $e;
+            }
+
             return trigger_error($e, E_USER_ERROR);
         }
 
@@ -912,7 +916,7 @@ class Request
      * ("Client-Ip" for instance), configure it via the $trustedHeaderSet
      * argument of the Request::setTrustedProxies() method instead.
      *
-     * @return string The client IP address
+     * @return string|null The client IP address
      *
      * @see getClientIps()
      * @see https://wikipedia.org/wiki/X-Forwarded-For
diff --git a/src/Symfony/Component/HttpFoundation/Response.php b/src/Symfony/Component/HttpFoundation/Response.php
index eae9b78414..8a17acdd5f 100644
--- a/src/Symfony/Component/HttpFoundation/Response.php
+++ b/src/Symfony/Component/HttpFoundation/Response.php
@@ -407,7 +407,7 @@ class Response
     /**
      * Gets the current response content.
      *
-     * @return string Content
+     * @return string|false
      */
     public function getContent()
     {
diff --git a/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php b/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php
index bbf2e39c81..07885e7fbf 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php
@@ -97,7 +97,7 @@ class NamespacedAttributeBag extends AttributeBag
      * @param string $name         Key name
      * @param bool   $writeContext Write context, default false
      *
-     * @return array
+     * @return array|null
      */
     protected function &resolveAttributePath($name, $writeContext = false)
     {
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/MemcachedSessionHandler.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/MemcachedSessionHandler.php
index 8965c089c1..a399be5fd8 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/MemcachedSessionHandler.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/MemcachedSessionHandler.php
@@ -40,9 +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
-     * @param array      $options   An associative array of Memcached options
-     *
      * @throws \InvalidArgumentException When unsupported options are passed
      */
     public function __construct(\Memcached $memcached, array $options = [])
@@ -58,7 +55,7 @@ class MemcachedSessionHandler extends AbstractSessionHandler
     }
 
     /**
-     * {@inheritdoc}
+     * @return bool
      */
     public function close()
     {
@@ -74,7 +71,7 @@ class MemcachedSessionHandler extends AbstractSessionHandler
     }
 
     /**
-     * {@inheritdoc}
+     * @return bool
      */
     public function updateTimestamp($sessionId, $data)
     {
@@ -102,7 +99,7 @@ class MemcachedSessionHandler extends AbstractSessionHandler
     }
 
     /**
-     * {@inheritdoc}
+     * @return bool
      */
     public function gc($maxlifetime)
     {
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/NullSessionHandler.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/NullSessionHandler.php
index 8d193155b0..3ba9378ca7 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/NullSessionHandler.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/NullSessionHandler.php
@@ -67,7 +67,7 @@ class NullSessionHandler extends AbstractSessionHandler
     }
 
     /**
-     * {@inheritdoc}
+     * @return bool
      */
     public function gc($maxlifetime)
     {
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
index 9a50377bcb..f9e5d1e8f0 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
@@ -286,7 +286,7 @@ class PdoSessionHandler extends AbstractSessionHandler
     }
 
     /**
-     * {@inheritdoc}
+     * @return bool
      */
     public function gc($maxlifetime)
     {
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/StrictSessionHandler.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/StrictSessionHandler.php
index 83a1f2c063..fab8e9a16d 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/StrictSessionHandler.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/StrictSessionHandler.php
@@ -94,7 +94,7 @@ class StrictSessionHandler extends AbstractSessionHandler
     }
 
     /**
-     * {@inheritdoc}
+     * @return bool
      */
     public function gc($maxlifetime)
     {
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/AbstractProxy.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/AbstractProxy.php
index 09c92483c7..0303729e7b 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/AbstractProxy.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/AbstractProxy.php
@@ -31,7 +31,7 @@ abstract class AbstractProxy
     /**
      * Gets the session.save_handler name.
      *
-     * @return string
+     * @return string|null
      */
     public function getSaveHandlerName()
     {
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/SessionHandlerProxy.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/SessionHandlerProxy.php
index b11cc397a0..e40712d93f 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/SessionHandlerProxy.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Proxy/SessionHandlerProxy.php
@@ -76,7 +76,7 @@ class SessionHandlerProxy extends AbstractProxy implements \SessionHandlerInterf
     }
 
     /**
-     * {@inheritdoc}
+     * @return bool
      */
     public function gc($maxlifetime)
     {
diff --git a/src/Symfony/Component/HttpFoundation/StreamedResponse.php b/src/Symfony/Component/HttpFoundation/StreamedResponse.php
index 8bc5fc91a5..b9148ea872 100644
--- a/src/Symfony/Component/HttpFoundation/StreamedResponse.php
+++ b/src/Symfony/Component/HttpFoundation/StreamedResponse.php
@@ -136,8 +136,6 @@ class StreamedResponse extends Response
 
     /**
      * {@inheritdoc}
-     *
-     * @return false
      */
     public function getContent()
     {
diff --git a/src/Symfony/Component/HttpFoundation/Tests/BinaryFileResponseTest.php b/src/Symfony/Component/HttpFoundation/Tests/BinaryFileResponseTest.php
index 3df96f393b..fcad11defa 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/BinaryFileResponseTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/BinaryFileResponseTest.php
@@ -107,7 +107,7 @@ class BinaryFileResponseTest extends ResponseTestCase
 
         $this->assertEquals(206, $response->getStatusCode());
         $this->assertEquals($responseRange, $response->headers->get('Content-Range'));
-        $this->assertSame($length, $response->headers->get('Content-Length'));
+        $this->assertSame((string) $length, $response->headers->get('Content-Length'));
     }
 
     /**
diff --git a/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Proxy/SessionHandlerProxyTest.php b/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Proxy/SessionHandlerProxyTest.php
index ec9029c7da..1457ebd70d 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Proxy/SessionHandlerProxyTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Proxy/SessionHandlerProxyTest.php
@@ -144,7 +144,8 @@ class SessionHandlerProxyTest extends TestCase
     {
         $mock = $this->getMockBuilder(['SessionHandlerInterface', 'SessionUpdateTimestampHandlerInterface'])->getMock();
         $mock->expects($this->once())
-            ->method('updateTimestamp');
+            ->method('updateTimestamp')
+            ->willReturn(false);
 
         $proxy = new SessionHandlerProxy($mock);
         $proxy->updateTimestamp('id', 'data');
diff --git a/src/Symfony/Component/HttpKernel/Tests/KernelTest.php b/src/Symfony/Component/HttpKernel/Tests/KernelTest.php
index a5a1919d54..9a19cd3ffe 100644
--- a/src/Symfony/Component/HttpKernel/Tests/KernelTest.php
+++ b/src/Symfony/Component/HttpKernel/Tests/KernelTest.php
@@ -22,6 +22,7 @@ use Symfony\Component\HttpKernel\Bundle\BundleInterface;
 use Symfony\Component\HttpKernel\Config\EnvParametersResource;
 use Symfony\Component\HttpKernel\DependencyInjection\ResettableServicePass;
 use Symfony\Component\HttpKernel\DependencyInjection\ServicesResetter;
+use Symfony\Component\HttpKernel\HttpKernel;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
 use Symfony\Component\HttpKernel\Kernel;
 use Symfony\Component\HttpKernel\Tests\Fixtures\KernelForOverrideName;
diff --git a/src/Symfony/Component/HttpKernel/Tests/Logger.php b/src/Symfony/Component/HttpKernel/Tests/Logger.php
index 8ae756132c..47529a2d34 100644
--- a/src/Symfony/Component/HttpKernel/Tests/Logger.php
+++ b/src/Symfony/Component/HttpKernel/Tests/Logger.php
@@ -22,6 +22,9 @@ class Logger implements LoggerInterface
         $this->clear();
     }
 
+    /**
+     * @return array
+     */
     public function getLogs($level = false)
     {
         return false === $level ? $this->logs : $this->logs[$level];
diff --git a/src/Symfony/Component/Process/Process.php b/src/Symfony/Component/Process/Process.php
index 9da1acefa4..7da0ee8fd4 100644
--- a/src/Symfony/Component/Process/Process.php
+++ b/src/Symfony/Component/Process/Process.php
@@ -71,7 +71,7 @@ class Process implements \IteratorAggregate
     private $status = self::STATUS_READY;
     private $incrementalOutputOffset = 0;
     private $incrementalErrorOutputOffset = 0;
-    private $tty;
+    private $tty = false;
     private $pty;
     private $inheritEnv = false;
 
diff --git a/src/Symfony/Component/Security/Http/RememberMe/RememberMeServicesInterface.php b/src/Symfony/Component/Security/Http/RememberMe/RememberMeServicesInterface.php
index fe8b0faee5..ae52591da0 100644
--- a/src/Symfony/Component/Security/Http/RememberMe/RememberMeServicesInterface.php
+++ b/src/Symfony/Component/Security/Http/RememberMe/RememberMeServicesInterface.php
@@ -46,7 +46,7 @@ interface RememberMeServicesInterface
      * make sure to throw an AuthenticationException as this will consequentially
      * result in a call to loginFail() and therefore an invalidation of the cookie.
      *
-     * @return TokenInterface
+     * @return TokenInterface|null
      */
     public function autoLogin(Request $request);
 
diff --git a/src/Symfony/Component/VarDumper/Dumper/AbstractDumper.php b/src/Symfony/Component/VarDumper/Dumper/AbstractDumper.php
index 4eb8e6f0c1..87195bb6a1 100644
--- a/src/Symfony/Component/VarDumper/Dumper/AbstractDumper.php
+++ b/src/Symfony/Component/VarDumper/Dumper/AbstractDumper.php
@@ -35,7 +35,7 @@ abstract class AbstractDumper implements DataDumperInterface, DumperInterface
     protected $indentPad = '  ';
     protected $flags;
 
-    private $charset;
+    private $charset = '';
 
     /**
      * @param callable|resource|string|null $output  A line dumper callable, an opened stream or an output path, defaults to static::$defaultOutput