diff --git a/core/lib/Drupal/Component/Datetime/DateTimePlus.php b/core/lib/Drupal/Component/Datetime/DateTimePlus.php
index c706f9e..2134ffb 100644
--- a/core/lib/Drupal/Component/Datetime/DateTimePlus.php
+++ b/core/lib/Drupal/Component/Datetime/DateTimePlus.php
@@ -36,10 +36,6 @@
  * to abort processing. The calling script can decide what to do about
  * errors by checking the hasErrors() method and using the messages in
  * the errors array.
- *
- * Translation of error messages is not handled in this class. Error
- * messages are all in English.
- *
  */
 class DateTimePlus extends \DateTime {
 
@@ -48,6 +44,10 @@ class DateTimePlus extends \DateTime {
   const PHP      = 'php';
   const INTL     = 'intl';
 
+  // The warning number of the message when an invalid date is converted
+  // to a valid date. The English message is 'The parsed date is invalid'.
+  const INVALID_DATE_WARNING = 11;
+
   /**
    * An array of possible date parts.
    */
@@ -160,7 +160,7 @@ public function __construct($time = 'now', $timezone = NULL, $format = NULL, $se
     $this->validate_format = !empty($settings['validate_format']) ? $settings['validate_format'] : TRUE;
     $this->langcode = !empty($settings['langcode']) ? $settings['langcode'] : NULL;
     $this->country = !empty($settings['country']) ? $settings['country'] : NULL;
-    $this->calendar = !empty($settings['calendar']) ? $settings['calendar'] : self::CALENDAR;
+    $this->calendar = !empty($settings['calendar']) ? $settings['calendar'] : static::CALENDAR;
 
     // Store the original input so it is available for validation.
     $this->input_time_raw = $time;
@@ -224,7 +224,7 @@ public function __construct($time = 'now', $timezone = NULL, $format = NULL, $se
    * http://www.serverphorums.com/read.php?7,555645
    */
   public function __toString() {
-    $format = self::FORMAT;
+    $format = static::FORMAT;
     return $this->format($format) . ' ' . $this->getTimeZone()->getName();
   }
 
@@ -303,7 +303,7 @@ public function inputIsObject() {
    */
   public function constructFromObject() {
     try {
-      $this->input_time_adjusted = $this->input_time_adjusted->format(self::FORMAT);
+      $this->input_time_adjusted = $this->input_time_adjusted->format(static::FORMAT);
       parent::__construct($this->input_time_adjusted, $this->input_timezone_adjusted);
     }
     catch (\Exception $e) {
@@ -362,13 +362,13 @@ public function inputIsArray() {
   public function constructFromArray() {
     try {
       parent::__construct('', $this->input_timezone_adjusted);
-      $this->input_time_adjusted = self::prepareArray($this->input_time_adjusted, TRUE);
-      if (self::checkArray($this->input_time_adjusted)) {
+      $this->input_time_adjusted = static::prepareArray($this->input_time_adjusted, TRUE);
+      if (static::checkArray($this->input_time_adjusted)) {
         // Even with validation, we can end up with a value that the
         // parent class won't handle, like a year outside the range
         // of -9999 to 9999, which will pass checkdate() but
         // fail to construct a date object.
-        $this->input_time_adjusted = self::arrayToISO($this->input_time_adjusted);
+        $this->input_time_adjusted = static::arrayToISO($this->input_time_adjusted);
         parent::__construct($this->input_time_adjusted, $this->input_timezone_adjusted);
       }
       else {
@@ -461,7 +461,7 @@ public function getErrors() {
     if (!empty($errors['errors'])) {
       $this->errors += $errors['errors'];
     }
-    if (!empty($errors['warnings']) && in_array('The parsed date was invalid', $errors['warnings'])) {
+    if (!empty($errors['warnings']) && array_key_exists(static::INVALID_DATE_WARNING, $errors['warnings'])) {
       $this->errors[] = 'The date is invalid.';
     }
   }
@@ -490,24 +490,24 @@ function hasErrors() {
    *   The date as an ISO string.
    */
   public static function arrayToISO($array, $force_valid_date = FALSE) {
-    $array = self::prepareArray($array, $force_valid_date);
+    $array = static::prepareArray($array, $force_valid_date);
     $input_time_adjusted = '';
     if ($array['year'] !== '') {
-      $input_time_adjusted = self::datePad(intval($array['year']), 4);
+      $input_time_adjusted = static::datePad(intval($array['year']), 4);
       if ($force_valid_date || $array['month'] !== '') {
-        $input_time_adjusted .= '-' . self::datePad(intval($array['month']));
+        $input_time_adjusted .= '-' . static::datePad(intval($array['month']));
         if ($force_valid_date || $array['day'] !== '') {
-          $input_time_adjusted .= '-' . self::datePad(intval($array['day']));
+          $input_time_adjusted .= '-' . static::datePad(intval($array['day']));
         }
       }
     }
     if ($array['hour'] !== '') {
       $input_time_adjusted .= $input_time_adjusted ? 'T' : '';
-      $input_time_adjusted .= self::datePad(intval($array['hour']));
+      $input_time_adjusted .= static::datePad(intval($array['hour']));
       if ($force_valid_date || $array['minute'] !== '') {
-        $input_time_adjusted .= ':' . self::datePad(intval($array['minute']));
+        $input_time_adjusted .= ':' . static::datePad(intval($array['minute']));
         if ($force_valid_date || $array['second'] !== '') {
-          $input_time_adjusted .= ':' . self::datePad(intval($array['second']));
+          $input_time_adjusted .= ':' . static::datePad(intval($array['second']));
         }
       }
     }
@@ -672,10 +672,10 @@ function canUseIntl() {
    */
   function format($format, $settings = array()) {
 
-    $format_string_type = isset($settings['format_string_type']) ? $settings['format_string_type'] : self::PHP;
+    $format_string_type = isset($settings['format_string_type']) ? $settings['format_string_type'] : static::PHP;
     $langcode = !empty($settings['langcode']) ? $settings['langcode'] : $this->langcode;
     $country = !empty($settings['country']) ? $settings['country'] : $this->country;
-    $calendar= !empty($settings['calendar']) ? $settings['calendar'] : $this->calendar;
+    $calendar = !empty($settings['calendar']) ? $settings['calendar'] : $this->calendar;
     $time_zone = !empty($settings['timezone']) ? $settings['timezone'] : $this->getTimezone()->getName();
     $lenient  = !empty($settings['lenient'])  ? $settings['lenient']  : FALSE;
 
@@ -683,13 +683,13 @@ function format($format, $settings = array()) {
     try {
 
       // If we have what we need to use the IntlDateFormatter, do so.
-      if ($this->canUseIntl() && $format_string_type == self::INTL) {
+      if ($this->canUseIntl() && $format_string_type == static::INTL) {
 
         // Construct the $locale variable needed by the IntlDateFormatter.
         $locale = $langcode . '_' . $country;
 
         // If we have information about a calendar, add it.
-        if (!empty($calendar) && $calendar != self::CALENDAR) {
+        if (!empty($calendar) && $calendar != static::CALENDAR) {
           $locale .= '@calendar=' . $calendar;
         }
 
diff --git a/core/lib/Drupal/Core/Datetime/DrupalDateTime.php b/core/lib/Drupal/Core/Datetime/DrupalDateTime.php
index eccafa5..9378406 100644
--- a/core/lib/Drupal/Core/Datetime/DrupalDateTime.php
+++ b/core/lib/Drupal/Core/Datetime/DrupalDateTime.php
@@ -72,10 +72,6 @@ public function __construct($time = 'now', $timezone = NULL, $format = NULL, $se
     // Instantiate the parent class.
     parent::__construct($time, $timezone, $format, $settings);
 
-    // Attempt to translate the error messages.
-    foreach ($this->errors as &$error) {
-      $error = t($error);
-    }
   }
 
   /**
@@ -128,7 +124,7 @@ public function __construct($time = 'now', $timezone = NULL, $format = NULL, $se
    */
   function format($format, $settings = array()) {
 
-    $format_string_type = isset($settings['format_string_type']) ? $settings['format_string_type'] : self::PHP;
+    $format_string_type = isset($settings['format_string_type']) ? $settings['format_string_type'] : static::PHP;
 
     $settings['langcode'] = !empty($settings['langcode']) ? $settings['langcode'] : $this->langcode;
     $settings['country'] = !empty($settings['country']) ? $settings['country'] : $this->country;
@@ -163,7 +159,7 @@ function format($format, $settings = array()) {
       }
     }
     catch (\Exception $e) {
-      $this->errors[] = t($e->getMessage());
+      $this->errors[] = $e->getMessage();
     }
     return $value;
   }