diff --git a/src/Symfony/Bridge/Twig/NodeVisitor/TranslationDefaultDomainNodeVisitor.php b/src/Symfony/Bridge/Twig/NodeVisitor/TranslationDefaultDomainNodeVisitor.php
index 04b68ef6be..be08d0d1d1 100644
--- a/src/Symfony/Bridge/Twig/NodeVisitor/TranslationDefaultDomainNodeVisitor.php
+++ b/src/Symfony/Bridge/Twig/NodeVisitor/TranslationDefaultDomainNodeVisitor.php
@@ -107,6 +107,8 @@ class TranslationDefaultDomainNodeVisitor extends AbstractNodeVisitor
 
     /**
      * {@inheritdoc}
+     *
+     * @return int
      */
     public function getPriority()
     {
diff --git a/src/Symfony/Bridge/Twig/NodeVisitor/TranslationNodeVisitor.php b/src/Symfony/Bridge/Twig/NodeVisitor/TranslationNodeVisitor.php
index 35e2eb21d0..1a399ce8ba 100644
--- a/src/Symfony/Bridge/Twig/NodeVisitor/TranslationNodeVisitor.php
+++ b/src/Symfony/Bridge/Twig/NodeVisitor/TranslationNodeVisitor.php
@@ -97,6 +97,8 @@ class TranslationNodeVisitor extends AbstractNodeVisitor
 
     /**
      * {@inheritdoc}
+     *
+     * @return int
      */
     public function getPriority()
     {
diff --git a/src/Symfony/Bridge/Twig/Translation/TwigExtractor.php b/src/Symfony/Bridge/Twig/Translation/TwigExtractor.php
index a921582dba..56427c762f 100644
--- a/src/Symfony/Bridge/Twig/Translation/TwigExtractor.php
+++ b/src/Symfony/Bridge/Twig/Translation/TwigExtractor.php
@@ -106,9 +106,7 @@ class TwigExtractor extends AbstractFileExtractor implements ExtractorInterface
     }
 
     /**
-     * @param string|array $directory
-     *
-     * @return array
+     * {@inheritdoc}
      */
     protected function extractFromDirectory($directory)
     {
diff --git a/src/Symfony/Component/Translation/DataCollector/TranslationDataCollector.php b/src/Symfony/Component/Translation/DataCollector/TranslationDataCollector.php
index 7aabcb24d5..fc713463a0 100644
--- a/src/Symfony/Component/Translation/DataCollector/TranslationDataCollector.php
+++ b/src/Symfony/Component/Translation/DataCollector/TranslationDataCollector.php
@@ -61,7 +61,7 @@ class TranslationDataCollector extends DataCollector implements LateDataCollecto
     }
 
     /**
-     * @return array
+     * @return array|Data
      */
     public function getMessages()
     {
diff --git a/src/Symfony/Component/Translation/Extractor/AbstractFileExtractor.php b/src/Symfony/Component/Translation/Extractor/AbstractFileExtractor.php
index 08a27fb07c..2da1fff6e6 100644
--- a/src/Symfony/Component/Translation/Extractor/AbstractFileExtractor.php
+++ b/src/Symfony/Component/Translation/Extractor/AbstractFileExtractor.php
@@ -21,9 +21,9 @@ use Symfony\Component\Translation\Exception\InvalidArgumentException;
 abstract class AbstractFileExtractor
 {
     /**
-     * @param string|array $resource Files, a file or a directory
+     * @param string|iterable $resource Files, a file or a directory
      *
-     * @return array
+     * @return iterable
      */
     protected function extractFiles($resource)
     {
@@ -79,7 +79,7 @@ abstract class AbstractFileExtractor
     /**
      * @param string|array $resource Files, a file or a directory
      *
-     * @return array files to be extracted
+     * @return iterable files to be extracted
      */
     abstract protected function extractFromDirectory($resource);
 }
diff --git a/src/Symfony/Component/Translation/Extractor/PhpExtractor.php b/src/Symfony/Component/Translation/Extractor/PhpExtractor.php
index 539f78ec85..ec2445d951 100644
--- a/src/Symfony/Component/Translation/Extractor/PhpExtractor.php
+++ b/src/Symfony/Component/Translation/Extractor/PhpExtractor.php
@@ -103,7 +103,7 @@ class PhpExtractor extends AbstractFileExtractor implements ExtractorInterface
      *
      * @param mixed $token
      *
-     * @return string
+     * @return string|null
      */
     protected function normalizeToken($token)
     {
@@ -257,9 +257,7 @@ class PhpExtractor extends AbstractFileExtractor implements ExtractorInterface
     }
 
     /**
-     * @param string|array $directory
-     *
-     * @return array
+     * {@inheritdoc}
      */
     protected function extractFromDirectory($directory)
     {
diff --git a/src/Symfony/Component/Translation/Loader/YamlFileLoader.php b/src/Symfony/Component/Translation/Loader/YamlFileLoader.php
index 771e6e7b7b..8d9aa6f72a 100644
--- a/src/Symfony/Component/Translation/Loader/YamlFileLoader.php
+++ b/src/Symfony/Component/Translation/Loader/YamlFileLoader.php
@@ -52,6 +52,10 @@ class YamlFileLoader extends FileLoader
             restore_error_handler();
         }
 
-        return $messages;
+        if (null !== $messages && !\is_array($messages)) {
+            throw new InvalidResourceException(sprintf('Unable to load file "%s".', $resource));
+        }
+
+        return $messages ?: [];
     }
 }