diff --git a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToArrayTransformer.php b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToArrayTransformer.php
index 07070952f5..9e5d06b12b 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToArrayTransformer.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToArrayTransformer.php
@@ -56,8 +56,7 @@ class DateTimeToArrayTransformer extends BaseDateTimeTransformer
      * @return array Localized date.
      *
      * @throws TransformationFailedException If the given value is not an
-     *                                       instance of \DateTime or if the
-     *                                       output timezone is not supported.
+     *                                       instance of \DateTime or \DateTimeInterface
      */
     public function transform($dateTime)
     {
@@ -81,11 +80,7 @@ class DateTimeToArrayTransformer extends BaseDateTimeTransformer
                 $dateTime = clone $dateTime;
             }
 
-            try {
-                $dateTime = $dateTime->setTimezone(new \DateTimeZone($this->outputTimezone));
-            } catch (\Exception $e) {
-                throw new TransformationFailedException($e->getMessage(), $e->getCode(), $e);
-            }
+            $dateTime = $dateTime->setTimezone(new \DateTimeZone($this->outputTimezone));
         }
 
         $result = array_intersect_key(array(
@@ -118,8 +113,6 @@ class DateTimeToArrayTransformer extends BaseDateTimeTransformer
      *
      * @throws TransformationFailedException If the given value is not an array,
      *                                       if the value could not be transformed
-     *                                       or if the input timezone is not
-     *                                       supported.
      */
     public function reverseTransform($value)
     {
diff --git a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToLocalizedStringTransformer.php b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToLocalizedStringTransformer.php
index 5418f7feae..585e6d2471 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToLocalizedStringTransformer.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToLocalizedStringTransformer.php
@@ -75,8 +75,8 @@ class DateTimeToLocalizedStringTransformer extends BaseDateTimeTransformer
      * @return string|array Localized date string/array.
      *
      * @throws TransformationFailedException If the given value is not an instance
-     *                                       of \DateTime or if the date could not
-     *                                       be transformed.
+     *                                       of \DateTime or \DateTimeInterface or
+     *                                       if the date could not be transformed.
      */
     public function transform($dateTime)
     {
@@ -105,8 +105,7 @@ class DateTimeToLocalizedStringTransformer extends BaseDateTimeTransformer
      * @return \DateTime Normalized date
      *
      * @throws TransformationFailedException if the given value is not a string,
-     *                                       if the date could not be parsed or
-     *                                       if the input timezone is not supported
+     *                                       if the date could not be parsed
      */
     public function reverseTransform($value)
     {
@@ -132,11 +131,7 @@ class DateTimeToLocalizedStringTransformer extends BaseDateTimeTransformer
         }
 
         if ('UTC' !== $this->inputTimezone) {
-            try {
-                $dateTime->setTimezone(new \DateTimeZone($this->inputTimezone));
-            } catch (\Exception $e) {
-                throw new TransformationFailedException($e->getMessage(), $e->getCode(), $e);
-            }
+            $dateTime->setTimezone(new \DateTimeZone($this->inputTimezone));
         }
 
         return $dateTime;
diff --git a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToRfc3339Transformer.php b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToRfc3339Transformer.php
index c78d80401a..9a80cb2b9b 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToRfc3339Transformer.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToRfc3339Transformer.php
@@ -19,7 +19,14 @@ use Symfony\Component\Form\Exception\TransformationFailedException;
 class DateTimeToRfc3339Transformer extends BaseDateTimeTransformer
 {
     /**
-     * {@inheritdoc}
+     * Transforms a normalized date into a localized date.
+     *
+     * @param \DateTime|\DateTimeInterface $dateTime A DateTime object
+     *
+     * @return string The formatted date.
+     *
+     * @throws TransformationFailedException If the given value is not an
+     *                                       instance of \DateTime or \DateTimeInterface
      */
     public function transform($dateTime)
     {
@@ -32,7 +39,10 @@ class DateTimeToRfc3339Transformer extends BaseDateTimeTransformer
         }
 
         if ($this->inputTimezone !== $this->outputTimezone) {
-            $dateTime = clone $dateTime;
+            if (!$dateTime instanceof \DateTimeImmutable) {
+                $dateTime = clone $dateTime;
+            }
+
             $dateTime = $dateTime->setTimezone(new \DateTimeZone($this->outputTimezone));
         }
 
@@ -40,7 +50,14 @@ class DateTimeToRfc3339Transformer extends BaseDateTimeTransformer
     }
 
     /**
-     * {@inheritdoc}
+     * Transforms a formatted string following RFC 3339 into a normalized date.
+     *
+     * @param string $rfc3339 Formatted string
+     *
+     * @return \DateTime Normalized date
+     *
+     * @throws TransformationFailedException If the given value is not a string,
+     *                                       if the value could not be transformed
      */
     public function reverseTransform($rfc3339)
     {
@@ -58,12 +75,8 @@ class DateTimeToRfc3339Transformer extends BaseDateTimeTransformer
             throw new TransformationFailedException($e->getMessage(), $e->getCode(), $e);
         }
 
-        if ($this->outputTimezone !== $dateTime->getTimezone()->getName()) {
-            try {
-                $dateTime->setTimezone(new \DateTimeZone($this->inputTimezone));
-            } catch (\Exception $e) {
-                throw new TransformationFailedException($e->getMessage(), $e->getCode(), $e);
-            }
+        if ($this->inputTimezone !== $dateTime->getTimezone()->getName()) {
+            $dateTime->setTimezone(new \DateTimeZone($this->inputTimezone));
         }
 
         if (preg_match('/(\d{4})-(\d{2})-(\d{2})/', $rfc3339, $matches)) {
diff --git a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToStringTransformer.php b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToStringTransformer.php
index 30b73ad83c..56dee35027 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToStringTransformer.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToStringTransformer.php
@@ -86,35 +86,30 @@ class DateTimeToStringTransformer extends BaseDateTimeTransformer
      * Transforms a DateTime object into a date string with the configured format
      * and timezone.
      *
-     * @param \DateTime|\DateTimeInterface $value A DateTime object
+     * @param \DateTime|\DateTimeInterface $dateTime A DateTime object
      *
      * @return string A value as produced by PHP's date() function
      *
-     * @throws TransformationFailedException If the given value is not a \DateTime
-     *                                       instance or if the output timezone
-     *                                       is not supported.
+     * @throws TransformationFailedException If the given value is not an
+     *                                       instance of \DateTime or \DateTimeInterface
      */
-    public function transform($value)
+    public function transform($dateTime)
     {
-        if (null === $value) {
+        if (null === $dateTime) {
             return '';
         }
 
-        if (!$value instanceof \DateTime && !$value instanceof \DateTimeInterface) {
+        if (!$dateTime instanceof \DateTime && !$dateTime instanceof \DateTimeInterface) {
             throw new TransformationFailedException('Expected a \DateTime or \DateTimeInterface.');
         }
 
-        if (!$value instanceof \DateTimeImmutable) {
-            $value = clone $value;
+        if (!$dateTime instanceof \DateTimeImmutable) {
+            $dateTime = clone $dateTime;
         }
 
-        try {
-            $value = $value->setTimezone(new \DateTimeZone($this->outputTimezone));
-        } catch (\Exception $e) {
-            throw new TransformationFailedException($e->getMessage(), $e->getCode(), $e);
-        }
+        $dateTime = $dateTime->setTimezone(new \DateTimeZone($this->outputTimezone));
 
-        return $value->format($this->generateFormat);
+        return $dateTime->format($this->generateFormat);
     }
 
     /**
@@ -125,8 +120,7 @@ class DateTimeToStringTransformer extends BaseDateTimeTransformer
      * @return \DateTime An instance of \DateTime
      *
      * @throws TransformationFailedException If the given value is not a string,
-     *                                       if the date could not be parsed or
-     *                                       if the input timezone is not supported.
+     *                                       or could not be transformed
      */
     public function reverseTransform($value)
     {
diff --git a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToTimestampTransformer.php b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToTimestampTransformer.php
index b8f5f381a5..7ae30ebbb1 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToTimestampTransformer.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToTimestampTransformer.php
@@ -29,20 +29,19 @@ class DateTimeToTimestampTransformer extends BaseDateTimeTransformer
      * @return int A timestamp
      *
      * @throws TransformationFailedException If the given value is not an instance
-     *                                       of \DateTime or if the output
-     *                                       timezone is not supported.
+     *                                       of \DateTime or \DateTimeInterface
      */
-    public function transform($value)
+    public function transform($dateTime)
     {
-        if (null === $value) {
+        if (null === $dateTime) {
             return;
         }
 
-        if (!$value instanceof \DateTime && !$value instanceof \DateTimeInterface) {
+        if (!$dateTime instanceof \DateTime && !$dateTime instanceof \DateTimeInterface) {
             throw new TransformationFailedException('Expected a \DateTime or \DateTimeInterface.');
         }
 
-        return $value->getTimestamp();
+        return $dateTime->getTimestamp();
     }
 
     /**
@@ -53,7 +52,7 @@ class DateTimeToTimestampTransformer extends BaseDateTimeTransformer
      * @return \DateTime A \DateTime object
      *
      * @throws TransformationFailedException If the given value is not a timestamp
-     *                                       or if the given timestamp is invalid.
+     *                                       or if the given timestamp is invalid
      */
     public function reverseTransform($value)
     {