diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
index 4688c192a0..1f5b30d6ee 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
@@ -210,6 +210,10 @@ class FrameworkExtension extends Extension
         }
 
         if ($this->isConfigEnabled($container, $config['session'])) {
+            if (!\extension_loaded('session')) {
+                throw new \LogicException('PHP extension "session" is required.');
+            }
+
             $this->sessionConfigEnabled = true;
             $this->registerSessionConfiguration($config['session'], $container, $loader);
             if (!empty($config['test'])) {
diff --git a/src/Symfony/Component/Finder/Finder.php b/src/Symfony/Component/Finder/Finder.php
index 7b7b1152ef..57685b0c60 100644
--- a/src/Symfony/Component/Finder/Finder.php
+++ b/src/Symfony/Component/Finder/Finder.php
@@ -562,7 +562,7 @@ class Finder implements \IteratorAggregate, \Countable
     /**
      * Searches files and directories which match defined rules.
      *
-     * @param string|array $dirs A directory path or an array of directories
+     * @param string|string[] $dirs A directory path or an array of directories
      *
      * @return $this
      *
diff --git a/src/Symfony/Component/Finder/Iterator/ExcludeDirectoryFilterIterator.php b/src/Symfony/Component/Finder/Iterator/ExcludeDirectoryFilterIterator.php
index 3c5a3f0e7c..eb37f1310e 100644
--- a/src/Symfony/Component/Finder/Iterator/ExcludeDirectoryFilterIterator.php
+++ b/src/Symfony/Component/Finder/Iterator/ExcludeDirectoryFilterIterator.php
@@ -25,7 +25,7 @@ class ExcludeDirectoryFilterIterator extends \FilterIterator implements \Recursi
 
     /**
      * @param \Iterator $iterator    The Iterator to filter
-     * @param array     $directories An array of directories to exclude
+     * @param string[]  $directories An array of directories to exclude
      */
     public function __construct(\Iterator $iterator, array $directories)
     {
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php b/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
index ce7027954e..9e03bfa41b 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php
@@ -103,6 +103,10 @@ class NativeSessionStorage implements SessionStorageInterface
      */
     public function __construct(array $options = [], $handler = null, MetadataBag $metaBag = null)
     {
+        if (!\extension_loaded('session')) {
+            throw new \LogicException('PHP extension "session" is required.');
+        }
+
         $options += [
             'cache_limiter' => '',
             'cache_expire' => 0,
diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/PhpBridgeSessionStorage.php b/src/Symfony/Component/HttpFoundation/Session/Storage/PhpBridgeSessionStorage.php
index 662ed5015a..8969e609aa 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/PhpBridgeSessionStorage.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/PhpBridgeSessionStorage.php
@@ -24,6 +24,10 @@ class PhpBridgeSessionStorage extends NativeSessionStorage
      */
     public function __construct($handler = null, MetadataBag $metaBag = null)
     {
+        if (!\extension_loaded('session')) {
+            throw new \LogicException('PHP extension "session" is required.');
+        }
+
         $this->setMetadataBag($metaBag);
         $this->setSaveHandler($handler);
     }
diff --git a/src/Symfony/Component/Serializer/Encoder/JsonEncode.php b/src/Symfony/Component/Serializer/Encoder/JsonEncode.php
index 681e3c4941..ea25c95597 100644
--- a/src/Symfony/Component/Serializer/Encoder/JsonEncode.php
+++ b/src/Symfony/Component/Serializer/Encoder/JsonEncode.php
@@ -47,14 +47,19 @@ class JsonEncode implements EncoderInterface
      */
     public function encode($data, $format, array $context = [])
     {
-        $jsonEncodeOptions = $context[self::OPTIONS] ?? $this->defaultContext[self::OPTIONS];
-        $encodedJson = json_encode($data, $jsonEncodeOptions);
+        $options = $context[self::OPTIONS] ?? $this->defaultContext[self::OPTIONS];
 
-        if (\PHP_VERSION_ID >= 70300 && (JSON_THROW_ON_ERROR & $jsonEncodeOptions)) {
+        try {
+            $encodedJson = json_encode($data, $options);
+        } catch (\JsonException $e) {
+            throw new NotEncodableValueException($e->getMessage(), 0, $e);
+        }
+
+        if (\PHP_VERSION_ID >= 70300 && (JSON_THROW_ON_ERROR & $options)) {
             return $encodedJson;
         }
 
-        if (JSON_ERROR_NONE !== json_last_error() && (false === $encodedJson || !($jsonEncodeOptions & JSON_PARTIAL_OUTPUT_ON_ERROR))) {
+        if (JSON_ERROR_NONE !== json_last_error() && (false === $encodedJson || !($options & JSON_PARTIAL_OUTPUT_ON_ERROR))) {
             throw new NotEncodableValueException(json_last_error_msg());
         }
 
diff --git a/src/Symfony/Component/Serializer/Normalizer/DenormalizableInterface.php b/src/Symfony/Component/Serializer/Normalizer/DenormalizableInterface.php
index 31e27a85cb..3e7021b130 100644
--- a/src/Symfony/Component/Serializer/Normalizer/DenormalizableInterface.php
+++ b/src/Symfony/Component/Serializer/Normalizer/DenormalizableInterface.php
@@ -34,7 +34,7 @@ interface DenormalizableInterface
      *                                                  differently based on different input formats
      * @param array                       $context      Options for denormalizing
      *
-     * @return object
+     * @return object|object[]
      */
     public function denormalize(DenormalizerInterface $denormalizer, $data, $format = null, array $context = []);
 }
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/AbstractComparisonValidatorTestCase.php b/src/Symfony/Component/Validator/Tests/Constraints/AbstractComparisonValidatorTestCase.php
index 2f27974a80..3a84694cc7 100644
--- a/src/Symfony/Component/Validator/Tests/Constraints/AbstractComparisonValidatorTestCase.php
+++ b/src/Symfony/Component/Validator/Tests/Constraints/AbstractComparisonValidatorTestCase.php
@@ -148,20 +148,6 @@ abstract class AbstractComparisonValidatorTestCase extends ConstraintValidatorTe
         $this->assertNoViolation();
     }
 
-    /**
-     * @dataProvider provideValidComparisonsToPropertyPath
-     */
-    public function testValidComparisonToPropertyPathOnArray($comparedValue)
-    {
-        $constraint = $this->createConstraint(['propertyPath' => '[root][value]']);
-
-        $this->setObject(['root' => ['value' => 5]]);
-
-        $this->validator->validate($comparedValue, $constraint);
-
-        $this->assertNoViolation();
-    }
-
     public function testNoViolationOnNullObjectWithPropertyPath()
     {
         $constraint = $this->createConstraint(['propertyPath' => 'propertyPath']);
diff --git a/src/Symfony/Component/Validator/Tests/Validator/AbstractTest.php b/src/Symfony/Component/Validator/Tests/Validator/AbstractTest.php
index 2bc3d11ef6..c9c05a0edf 100644
--- a/src/Symfony/Component/Validator/Tests/Validator/AbstractTest.php
+++ b/src/Symfony/Component/Validator/Tests/Validator/AbstractTest.php
@@ -511,7 +511,7 @@ abstract class AbstractTest extends AbstractValidatorTest
                 ->setParameter('%param%', 'value')
                 ->setInvalidValue('Invalid value')
                 ->setPlural(2)
-                ->setCode(42)
+                ->setCode('42')
                 ->addViolation();
         };
 
@@ -528,7 +528,7 @@ abstract class AbstractTest extends AbstractValidatorTest
         $this->assertSame($entity, $violations[0]->getRoot());
         $this->assertSame('Invalid value', $violations[0]->getInvalidValue());
         $this->assertSame(2, $violations[0]->getPlural());
-        $this->assertSame(42, $violations[0]->getCode());
+        $this->assertSame('42', $violations[0]->getCode());
     }
 
     public function testNoDuplicateValidationIfClassConstraintInMultipleGroups()