diff --git a/core/lib/Drupal/Core/Render/Element/RenderElement.php b/core/lib/Drupal/Core/Render/Element/RenderElement.php
index a6e4492..73b4c36 100644
--- a/core/lib/Drupal/Core/Render/Element/RenderElement.php
+++ b/core/lib/Drupal/Core/Render/Element/RenderElement.php
@@ -129,11 +129,10 @@ public static function preRenderGroup($element) {
    * @see self::preRenderAjaxForm()
    */
   public static function processAjaxForm(&$element, FormStateInterface $form_state, &$complete_form) {
-    $element = static::preRenderAjaxForm($element);
-    if (!empty($element['#ajax']['cache_form'])) {
+    if (!empty($element['#ajax']['url'])) {
       $form_state->setCached();
     }
-    return $element;
+    return static::preRenderAjaxForm($element);
   }
 
   /**
@@ -154,7 +153,6 @@ public static function processAjaxForm(&$element, FormStateInterface $form_state
    *   - #ajax['parameters']
    *   - #ajax['effect']
    *   - #ajax['accepts']
-   *   - #ajax['cache_form']
    *
    * @return array
    *   The processed element with the necessary JavaScript attached to it.
diff --git a/core/modules/file/src/Element/ManagedFile.php b/core/modules/file/src/Element/ManagedFile.php
index d6f7419..4bfd6ca 100644
--- a/core/modules/file/src/Element/ManagedFile.php
+++ b/core/modules/file/src/Element/ManagedFile.php
@@ -145,9 +145,8 @@ public static function processManagedFile(&$element, FormStateInterface $form_st
     $element['#tree'] = TRUE;
 
     $ajax_settings = [
-      'url' => Url::fromRoute('file.ajax_upload'),
       // @todo Remove this in https://www.drupal.org/node/2500527.
-      'cache_form' => TRUE,
+      'url' => Url::fromRoute('file.ajax_upload'),
       'options' => [
         'query' => [
           'element_parents' => implode('/', $element['#array_parents']),
diff --git a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestSimpleForm.php b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestSimpleForm.php
index 5289bcd..1f76850 100644
--- a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestSimpleForm.php
+++ b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestSimpleForm.php
@@ -71,9 +71,8 @@ public function buildForm(array $form, FormStateInterface $form_state) {
         '#options' => array('red' => 'red'),
         '#ajax' => array(
           'callback' => $value,
-          // If the callback is NULL, the form will not post to the original URL
-          // and will expect the form to be cached.
-          'cache_form' => $value === NULL,
+          // If the callback is NULL, the URL needs to be specified.
+          'url' => $value === NULL ? Url::fromRoute('system.ajax') : NULL,
         ),
       );
     }
diff --git a/core/modules/views_ui/admin.inc b/core/modules/views_ui/admin.inc
index 9cc4af8..7e07366 100644
--- a/core/modules/views_ui/admin.inc
+++ b/core/modules/views_ui/admin.inc
@@ -55,7 +55,6 @@ function views_ui_add_ajax_trigger(&$wrapping_element, $trigger_key, $refresh_pa
   // Specify the #ajax URL in order to retain form caching.
   // @todo Remove this in https://www.drupal.org/node/2500523.
   $triggering_element['#ajax']['url'] = Url::fromRoute('system.ajax');
-  $triggering_element['#ajax']['cache_form'] = TRUE;
 
   // We do not use \Drupal\Component\Utility\Html::getUniqueId() to get an ID
   // for the AJAX wrapper, because it remembers IDs across AJAX requests (and