Issue #3393401: InvalidArgumentException: The timestamp must be numeric. in...

Issue #3393401:  InvalidArgumentException: The timestamp must be numeric. in Drupal\Component\Datetime\DateTimePlus::createFromTimestamp()

src/Entity/MailEntityQueueItem.php

@@ -146,6 +146,15 @@ class MailEntityQueueItem extends ContentEntityBase implements MailEntityQueueIt
     ];
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function preSave(EntityStorageInterface $storage) {
+    $this->setChangedTime(\Drupal::time()->getRequestTime());
+
+    parent::preSave($storage);
+  }
+
   /**
    * {@inheritdoc}
    */