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