Fatal error: Uncaught Error: Class "Drupal\Component\Render\FormattableMarkup" not found in /home/www/drupal8/test/core/lib/Drupal/Core/StringTranslation/TranslatableMarkup.php:21 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/StringTranslation/TranslatableMarkup.php on line 21