Fatal error: Uncaught Error: Interface "Drupal\hal\LinkManager\RelationLinkManagerInterface" not found in /home/www/drupal8/test/core/modules/rest/src/LinkManager/RelationLinkManagerInterface.php:13 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/rest/src/LinkManager/RelationLinkManagerInterface.php on line 13