Fatal error: Uncaught Error: Interface "Drupal\Component\Gettext\PoWriterInterface" not found in /home/www/drupal8/test/core/lib/Drupal/Component/Gettext/PoStreamWriter.php:8 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Component/Gettext/PoStreamWriter.php on line 8