Fatal error: Uncaught Error: Class "Drupal\Core\Menu\MenuLinkBase" not found in /home/www/drupal8/test/core/modules/menu_link_content/src/Plugin/Menu/MenuLinkContent.php:15 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/menu_link_content/src/Plugin/Menu/MenuLinkContent.php on line 15