Fatal error: Uncaught Error: Interface "Drupal\Component\Plugin\Context\ContextInterface" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Plugin/Context/ContextInterface.php:14 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Plugin/Context/ContextInterface.php on line 14