diff -u b/core/misc/vertical-tabs.es6.js b/core/misc/vertical-tabs.es6.js
--- b/core/misc/vertical-tabs.es6.js
+++ b/core/misc/vertical-tabs.es6.js
@@ -127,7 +127,7 @@
    *   The name of the tab.
    * @param {jQuery} settings.details
    *   The jQuery object of the details element that is the tab pane.
-   * @param {jQuery} settings.childErrorCount
+   * @param {number} settings.childErrorCount
    *   The number of form errors contained inside the tab pane.
    *
    * @fires event:summaryUpdated
@@ -254,7 +254,7 @@
    *   The name of the tab.
    * @param {jQuery} settings.details
    *   The jQuery object of the details element that is the tab pane.
-   * @param {jQuery} settings.childErrorCount
+   * @param {number} settings.childErrorCount
    *   The number of form errors contained inside the tab pane.
    *
    * @return {object}
diff -u b/core/modules/system/tests/modules/form_test/form_test.routing.yml b/core/modules/system/tests/modules/form_test/form_test.routing.yml
--- b/core/modules/system/tests/modules/form_test/form_test.routing.yml
+++ b/core/modules/system/tests/modules/form_test/form_test.routing.yml
@@ -459,14 +459,6 @@
   requirements:
     _access: 'TRUE'
 
-form_test.child_error_vertical_tabs:
-  path: '/form-test/child-error-vertical-tabs'
-  defaults:
-    _form: '\Drupal\form_test\Form\FormTestChildErrorVerticalTabsForm'
-    _title: 'Child element error vertical tabs testing'
-  requirements:
-    _access: 'TRUE'
-
 form_test.two_instances:
   path: '/form-test/two-instances-of-same-form'
   defaults:
@@ -475,6 +467,14 @@
   requirements:
     _access: 'TRUE'
 
+form_test.child_error_vertical_tabs:
+  path: '/form-test/child-error-vertical-tabs'
+  defaults:
+    _form: '\Drupal\form_test\Form\FormTestChildErrorVerticalTabsForm'
+    _title: 'Child element error vertical tabs testing'
+  requirements:
+    _access: 'TRUE'
+
 form_test.two_instances:
   path: '/form-test/two-instances-of-same-form'
   defaults: