diff --git a/core/modules/block/custom_block/custom_block.routing.yml b/core/modules/block/custom_block/custom_block.routing.yml
index e3b0d8748940..cad1f094b153 100644
--- a/core/modules/block/custom_block/custom_block.routing.yml
+++ b/core/modules/block/custom_block/custom_block.routing.yml
@@ -9,7 +9,7 @@ custom_block.type_list:
 custom_block.add_page:
   path: '/block/add'
   defaults:
-    _content: 'Drupal\custom_block\Controller\CustomBlockController::add'
+    _content: '\Drupal\custom_block\Controller\CustomBlockController::add'
     _title: 'Add custom block'
   options:
     _admin_route: TRUE
@@ -19,7 +19,7 @@ custom_block.add_page:
 custom_block.add_form:
   path: '/block/add/{custom_block_type}'
   defaults:
-    _content: 'Drupal\custom_block\Controller\CustomBlockController::addForm'
+    _content: '\Drupal\custom_block\Controller\CustomBlockController::addForm'
     _title_callback: 'Drupal\custom_block\Controller\CustomBlockController::getAddFormTitle'
   options:
     _admin_route: TRUE
diff --git a/core/modules/comment/comment.routing.yml b/core/modules/comment/comment.routing.yml
index e3ad589dfb5d..1a6ac597e2f1 100644
--- a/core/modules/comment/comment.routing.yml
+++ b/core/modules/comment/comment.routing.yml
@@ -69,7 +69,7 @@ comment.new_comments_node_links:
 comment.bundle_list:
   path: '/admin/structure/comments'
   defaults:
-    _content: 'Drupal\comment\Controller\AdminController::overviewBundles'
+    _content: '\Drupal\comment\Controller\AdminController::overviewBundles'
     _title: 'Comment forms'
   requirements:
     _permission: 'administer comments'
diff --git a/core/modules/locale/locale.routing.yml b/core/modules/locale/locale.routing.yml
index 705d5ea434ee..a5703d802265 100644
--- a/core/modules/locale/locale.routing.yml
+++ b/core/modules/locale/locale.routing.yml
@@ -16,7 +16,7 @@ locale.check_translation:
 locale.translate_page:
   path: '/admin/config/regional/translate'
   defaults:
-    _content: 'Drupal\locale\Controller\LocaleController::translatePage'
+    _content: '\Drupal\locale\Controller\LocaleController::translatePage'
     _title: 'User interface translation'
   requirements:
     _permission: 'translate interface'
diff --git a/core/modules/system/system.routing.yml b/core/modules/system/system.routing.yml
index b7eabf2accb5..13019c2e0156 100644
--- a/core/modules/system/system.routing.yml
+++ b/core/modules/system/system.routing.yml
@@ -272,7 +272,7 @@ system.theme_enable:
 system.status:
   path: '/admin/reports/status'
   defaults:
-    _content: 'Drupal\system\Controller\SystemInfoController::status'
+    _content: '\Drupal\system\Controller\SystemInfoController::status'
     _title: 'Status report'
   requirements:
     _permission: 'administer site configuration'
@@ -291,7 +291,7 @@ system.php:
 system.admin_index:
   path: '/admin/index'
   defaults:
-    _content: 'Drupal\system\Controller\AdminController::index'
+    _content: '\Drupal\system\Controller\AdminController::index'
     _title: 'Administration'
   requirements:
     _permission: 'access administration pages'
diff --git a/core/modules/system/tests/modules/test_page_test/test_page_test.routing.yml b/core/modules/system/tests/modules/test_page_test/test_page_test.routing.yml
index d9b016f3a574..784d6d77c1a9 100644
--- a/core/modules/system/tests/modules/test_page_test/test_page_test.routing.yml
+++ b/core/modules/system/tests/modules/test_page_test/test_page_test.routing.yml
@@ -9,14 +9,14 @@ test_page_test.test_page:
 test_page_test.render_title:
   path: '/test-render-title'
   defaults:
-    _content: 'Drupal\test_page_test\Controller\Test::renderTitle'
+    _content: '\Drupal\test_page_test\Controller\Test::renderTitle'
   requirements:
     _access: 'TRUE'
 
 test_page_test.static_title:
   path: '/test-page-static-title'
   defaults:
-    _content: 'Drupal\test_page_test\Controller\Test::staticTitle'
+    _content: '\Drupal\test_page_test\Controller\Test::staticTitle'
     _title: 'Static title'
   requirements:
     _access: 'TRUE'
@@ -24,7 +24,7 @@ test_page_test.static_title:
 test_page_test.dynamic_title:
   path: '/test-page-dynamic-title'
   defaults:
-    _content: 'Drupal\test_page_test\Controller\Test::staticTitle'
+    _content: '\Drupal\test_page_test\Controller\Test::staticTitle'
     _title_callback: 'Drupal\test_page_test\Controller\Test::dynamicTitle'
   requirements:
     _access: 'TRUE'
@@ -32,6 +32,6 @@ test_page_test.dynamic_title:
 test_page_test.admin_render_title:
   path: '/admin/test-render-title'
   defaults:
-    _content: 'Drupal\test_page_test\Controller\Test::renderTitle'
+    _content: '\Drupal\test_page_test\Controller\Test::renderTitle'
   requirements:
     _access: 'TRUE'