reverted:
--- b/core/misc/ajax.js
+++ a/core/misc/ajax.js
@@ -50,7 +50,25 @@
         }
       }
 
+      // Bind Ajax behaviors to all items showing the class.
+      $('.use-ajax').once('ajax').each(function () {
+        var element_settings = {};
+        // Clicked links look better with the throbber than the progress bar.
+        element_settings.progress = {type: 'throbber'};
+
+        // For anchor tags, these will go to the target of the anchor rather
+        // than the usual location.
+        var href = $(this).attr('href');
+        if (href) {
+          element_settings.url = href;
+          element_settings.event = 'click';
+        }
+        element_settings.dialogType = $(this).data('dialog-type');
+        element_settings.dialog = $(this).data('dialog-options');
+        element_settings.base = $(this).attr('id');
+        element_settings.element = this;
+        Drupal.ajax(element_settings);
+      });
-      Drupal.ajax.bindAjaxLinks($(window));
 
       // This class means to submit the form to the action using Ajax.
       $('.use-ajax-submit').once('ajax').each(function () {
@@ -259,34 +277,6 @@
   };
 
   /**
-   * Bind Ajax functionality to links that use the 'use-ajax' class.
-   *
-   * @param $element
-   *   Element to enable Ajax functionality for.
-   */
-  Drupal.ajax.bindAjaxLinks = function ($element) {
-    // Bind Ajax behaviors to all items showing the class.
-    $element.find('.use-ajax').once('ajax').each(function () {
-      var element_settings = {};
-      // Clicked links look better with the throbber than the progress bar.
-      element_settings.progress = {type: 'throbber'};
-
-      // For anchor tags, these will go to the target of the anchor rather
-      // than the usual location.
-      var href = $(this).attr('href');
-      if (href) {
-        element_settings.url = href;
-        element_settings.event = 'click';
-      }
-      element_settings.dialogType = $(this).data('dialog-type');
-      element_settings.dialog = $(this).data('dialog-options');
-      element_settings.base = $(this).attr('id');
-      element_settings.element = this;
-      Drupal.ajax(element_settings);
-    });
-  };
-
-  /**
    * Settings for an Ajax object.
    *
    * @typedef {object} Drupal.Ajax~element_settings
diff -u b/core/modules/contextual/js/contextual.js b/core/modules/contextual/js/contextual.js
--- b/core/modules/contextual/js/contextual.js
+++ b/core/modules/contextual/js/contextual.js
@@ -81,9 +81,6 @@
     // trigger the model change event handler in its views.
     contextual.collection.add(model);
 
-    // Enable Ajax functionality for contextual links.
-    Drupal.ajax.bindAjaxLinks($region);
-
     // Let other JavaScript react to the adding of a new contextual link.
     $(document).trigger('drupalContextualLinkAdded', {
       $el: $contextual,
@@ -212,6 +209,12 @@
           }
         });
       }
+
+
+      // Let other JavaScript react to the adding of a new contextual link.
+      $(document).once('contextual-ajax').on('drupalContextualLinkAdded', function (event, data) {
+        Drupal.attachBehaviors(data.$el[0]);
+      });
     }
   };
 
diff -u b/core/modules/contextual/tests/modules/contextual_ajax_test/contextual_ajax_test.module b/core/modules/contextual/tests/modules/contextual_ajax_test/contextual_ajax_test.module
--- b/core/modules/contextual/tests/modules/contextual_ajax_test/contextual_ajax_test.module
+++ b/core/modules/contextual/tests/modules/contextual_ajax_test/contextual_ajax_test.module
@@ -11,7 +11,6 @@
  * Change Configure Blocks into modal links.
  */
 function contextual_ajax_test_contextual_links_view_alter(&$element, $items) {
-  drupal_set_message('fffff');
   if (isset($element['#links']['contextual-ajax-test'])) {
     $element['#links']['contextual-ajax-test']['attributes'] = [
       'class' => ['use-ajax'],