reverted:
--- b/core/lib/Drupal/Core/Render/Element/StatusMessages.php
+++ a/core/lib/Drupal/Core/Render/Element/StatusMessages.php
@@ -37,9 +37,6 @@
       '#pre_render' => [
         get_class() . '::generatePlaceholder',
       ],
-      '#attached' => [
-        'library' => ['core/drupal.message'],
-      ],
     ];
   }
 
diff -u b/core/misc/message.js b/core/misc/message.js
--- b/core/misc/message.js
+++ b/core/misc/message.js
@@ -16,7 +16,7 @@
   Drupal.behaviors.drupalMessage = {
     attach: function () {
       if (!messagesElement) {
-        messagesElement = document.querySelector('[data-drupal-messages]');
+        messagesElement = $('[data-drupal-messages]');
         if (!messagesElement) {
           throw new Error(Drupal.t("There is no element with a [data-drupal-messages] attribute"));
         }
@@ -30,10 +30,10 @@
    */
   function processMessages () {
     var text = [],
-        message, n, nl;
+        message, messagesIndex, messagesLength;
 
     if (messages.length) {
-      for (n = 0, nl = messages.length; n < nl; n++) {
+      for (messagesIndex = 0, messagesLength = messages.length; messagesIndex < messagesLength; messagesIndex++) {
         message = messages.pop();
         text.unshift(Drupal.theme('message', message));
       }