diff -u b/core/modules/system/system.module b/core/modules/system/system.module
--- b/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -169,14 +169,6 @@
     'block__system_messages_block' => array(
       'base hook' => 'block',
     ),
-    'block__system_local_actions_block' => [
-      'base hook' => 'block',
-      'template' => 'block--system-page-actions-block',
-    ],
-    'block__system_tabs_block' => [
-      'base hook' => 'block',
-      'template' => 'block--system-page-tabs-block',
-    ],
     'block__system_menu_block' => array(
       'render element' => 'elements',
       'base hook' => 'block',