diff --git a/core/modules/system/lib/Drupal/system/Form/DateFormatFormBase.php b/core/modules/system/lib/Drupal/system/Form/DateFormatFormBase.php
index 1f7e143..480cacd 100644
--- a/core/modules/system/lib/Drupal/system/Form/DateFormatFormBase.php
+++ b/core/modules/system/lib/Drupal/system/Form/DateFormatFormBase.php
@@ -197,8 +197,8 @@ public function validate(array $form, array &$form_state) {
     // name, check to see if the provided pattern exists.
     $pattern = trim($form_state['values']['date_format_pattern']);
     foreach ($this->dateFormatStorage->loadMultiple() as $format) {
-      if ($format->getPattern() == $pattern && ($this->entity->isNew() || $format->id() != $this->entity->id())) {
-        form_set_error('date_format_pattern', t('This format already exists. Enter a unique format string.'));
+      if ($format->getPattern() == $pattern && ($format->id() == $this->entity->id())) {
+        drupal_set_message(t('The existing format/name combination has not been altered.'));
         continue;
       }
     }