Fatal error: Uncaught Error: Class "Drupal\Core\PageCache\ChainRequestPolicy" not found in /home/www/drupal8/test/core/lib/Drupal/Core/PageCache/DefaultRequestPolicy.php:16 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/PageCache/DefaultRequestPolicy.php on line 16