diff --git a/core/lib/Drupal/Core/Menu/LocalTaskManager.php b/core/lib/Drupal/Core/Menu/LocalTaskManager.php
index a7bd6cf..3ae67fd 100644
--- a/core/lib/Drupal/Core/Menu/LocalTaskManager.php
+++ b/core/lib/Drupal/Core/Menu/LocalTaskManager.php
@@ -41,12 +41,12 @@ class LocalTaskManager extends DefaultPluginManager {
     // The plugin ID of the parent tab (or NULL for the top-level tab).
     'tab_parent_id' => NULL,
     // The weight of the tab.
-    'weight' => 0,
+    'weight' => NULL,
     // The default link options.
     'options' => array(),
     // Default class for local task implementations.
     'class' => 'Drupal\Core\Menu\LocalTaskDefault',
-    // The plugin id. Set by the plugin system and should never be provided in YAML.
+    // The plugin id. Set by the plugin system based on the top-level YAML key.
     'id' => '',
   );
 
diff --git a/core/modules/system/tests/modules/menu_test/menu_test.local_tasks.yml b/core/modules/system/tests/modules/menu_test/menu_test.local_tasks.yml
index 7a6536a..e0e3bce 100644
--- a/core/modules/system/tests/modules/menu_test/menu_test.local_tasks.yml
+++ b/core/modules/system/tests/modules/menu_test/menu_test.local_tasks.yml
@@ -6,7 +6,6 @@ menu_local_task_test_tasks_edit:
   route_name: menu_local_task_test_tasks_edit
   title: Edit
   tab_root_id: menu_local_task_test_tasks_view
-  weight: 10
 menu_local_task_test_tasks_settings:
   route_name: menu_local_task_test_tasks_settings
   title: Settings