Fatal error: Uncaught Error: Interface "Drupal\Core\Field\FieldDefinitionInterface" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Field/FieldConfigInterface.php:17
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Field/FieldConfigInterface.php on line 17