Fatal error: Uncaught Error: Class "Drupal\block\BlockForm" not found in /home/www/drupal8/test/core/modules/settings_tray/src/Block/BlockEntitySettingTrayForm.php:24 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/settings_tray/src/Block/BlockEntitySettingTrayForm.php on line 24