diff --git a/core/core.api.php b/core/core.api.php
index b1fb3a2dd2..0a92352654 100644
--- a/core/core.api.php
+++ b/core/core.api.php
@@ -2339,20 +2339,21 @@ function hook_validation_constraint_alter(array &$definitions) {
  * an array. Here are the details of its elements, all of which are optional:
  * - callback: The callback to invoke to handle the server side of the
  *   Ajax event. More information on callbacks is below in @ref sub_callback.
- * - wrapper: The HTML 'id' attribute of the area where the content returned by
- *   the callback should be placed. Note that callbacks have a choice of
- *   returning content or JavaScript commands; 'wrapper' is used for content
- *   returns.
+ * - wrapper_selector: The CSS selector of the area where the content returned
+ *   by the callback should be placed. Note that callbacks have a choice of
+ *   returning content or JavaScript commands; 'wrapper_selector' is used for
+ *   content returns.
  * - method: The jQuery method for placing the new content (used with
- *   'wrapper'). Valid options are 'replaceWith' (default), 'append', 'prepend',
- *   'before', 'after', or 'html'. See
+ *   'wrapper_selector'). Valid options are 'replaceWith' (default), 'append',
+ *   'prepend', 'before', 'after', or 'html'. See
  *   http://api.jquery.com/category/manipulation/ for more information on these
  *   methods.
  * - effect: The jQuery effect to use when placing the new HTML (used with
- *   'wrapper'). Valid options are 'none' (default), 'slide', or 'fade'.
- * - speed: The effect speed to use (used with 'effect' and 'wrapper'). Valid
- *   options are 'slow' (default), 'fast', or the number of milliseconds the
- *   effect should run.
+ *   'wrapper_selector'). Valid options are 'none' (default), 'slide', or
+ *   'fade'.
+ * - speed: The effect speed to use (used with 'effect' and 'wrapper_selector').
+ *   Valid options are 'slow' (default), 'fast', or the number of milliseconds
+ *   the effect should run.
  * - event: The JavaScript event to respond to. This is selected automatically
  *   for the type of form element; provide a value to override the default.
  * - prevent: A JavaScript event to prevent when the event is triggered. For
@@ -2392,8 +2393,8 @@ function hook_validation_constraint_alter(array &$definitions) {
  * Once you have processed the input, you have your choice of returning HTML
  * markup or a set of Ajax commands. If you choose to return HTML markup, you
  * can return it as a string or a renderable array, and it will be placed in
- * the defined 'wrapper' element (see documentation above in @ref sub_form).
- * In addition, any messages returned by
+ * the defined 'wrapper_selector' element (see documentation above in
+ * @ref sub_form). In addition, any messages returned by
  * \Drupal\Core\Messenger\Messenger::all(), themed as in
  * status-messages.html.twig, will be prepended.
  *
@@ -2417,8 +2418,8 @@ function hook_validation_constraint_alter(array &$definitions) {
  * invokes an arbitrary jQuery command.
  *
  * As noted above, status messages are prepended automatically if you use the
- * 'wrapper' method and return HTML markup. This is not the case if you return
- * commands, but if you would like to show status messages, you can add
+ * 'wrapper_selector' method and return HTML markup. This is not the case if you
+ * return commands, but if you would like to show status messages, you can add
  * @code
  * array('#type' => 'status_messages')
  * @endcode
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
index 43cd540bb2..62111412f3 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -666,7 +666,7 @@ public static function fieldSettingsAjaxProcessElement(&$element, $main_form) {
     if (!empty($element['#ajax'])) {
       $element['#ajax'] = [
         'callback' => [static::class, 'settingsAjax'],
-        'wrapper' => $main_form['#id'],
+        'wrapper_selector' => '#' . $main_form['#id'],
         'element' => $main_form['#array_parents'],
       ];
     }
diff --git a/core/lib/Drupal/Core/Field/WidgetBase.php b/core/lib/Drupal/Core/Field/WidgetBase.php
index 39daf849aa..9fe6bdeb74 100644
--- a/core/lib/Drupal/Core/Field/WidgetBase.php
+++ b/core/lib/Drupal/Core/Field/WidgetBase.php
@@ -263,7 +263,7 @@ protected function formMultipleElements(FieldItemListInterface $items, array &$f
           '#submit' => [[static::class, 'addMoreSubmit']],
           '#ajax' => [
             'callback' => [static::class, 'addMoreAjax'],
-            'wrapper' => $wrapper_id,
+            'wrapper_selector' => '#' . $wrapper_id,
             'effect' => 'fade',
           ],
         ];
diff --git a/core/lib/Drupal/Core/Render/Element/RenderElement.php b/core/lib/Drupal/Core/Render/Element/RenderElement.php
index 627b041e04..389346ca42 100644
--- a/core/lib/Drupal/Core/Render/Element/RenderElement.php
+++ b/core/lib/Drupal/Core/Render/Element/RenderElement.php
@@ -246,7 +246,7 @@ public static function processAjaxForm(&$element, FormStateInterface $form_state
    *   - #ajax['url']
    *   - #ajax['callback']
    *   - #ajax['options']
-   *   - #ajax['wrapper']
+   *   - #ajax['wrapper_selector']
    *   - #ajax['parameters']
    *   - #ajax['effect']
    *   - #ajax['accepts']
@@ -331,6 +331,13 @@ public static function preRenderAjaxForm($element) {
 
       $settings = $element['#ajax'];
 
+      // @todo Remove support for 'wrapper' and solely use 'wrapper_selector'.
+      if (isset($settings['wrapper'])) {
+        @trigger_error('Use of "wrapper" is deprecated in drupal:9.1.0 and will be removed before drupal:10.0.0. Use "wrapper_selector" instead and prefix the value with either "#" for IDs or "." for classes.', E_USER_DEPRECATED);
+        $settings['wrapper_selector'] = '#' . $settings['wrapper'];
+        unset($settings['wrapper']);
+      }
+
       // Assign default settings. When 'url' is set to NULL, ajax.js submits the
       // Ajax request to the same URL as the form or link destination is for
       // someone with JavaScript disabled. This is generally preferred as a way to
diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 31959e6414..94007e6d1a 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -410,11 +410,12 @@
     //   - Call this 'selector'.
     //   - Include the '#' for ID-based selectors.
     //   - Support non-ID-based selectors.
-    if (this.wrapper) {
+    if (this.wrapper && !this.wrapper_selector) {
       /**
        * @type {string}
        */
-      this.wrapper = `#${this.wrapper}`;
+      this.wrapper_selector = '#'.concat(this.wrapper);
+      this.wrapper = this.wrapper_selector;
     }
 
     /**
@@ -1156,7 +1157,7 @@
       this.progress.object.stopMonitoring();
     }
     // Undo hide.
-    $(this.wrapper).show();
+    $(this.wrapper_selector).show();
     // Re-enable the element.
     $(this.element).prop('disabled', false);
     // Reattach behaviors, if they were detached in beforeSerialize(), and the
@@ -1274,7 +1275,7 @@
       // our presets.
       const $wrapper = response.selector
         ? $(response.selector)
-        : $(ajax.wrapper);
+        : $(ajax.wrapper_selector);
       const method = response.method || ajax.method;
       const effect = ajax.getEffect(response);
 
diff --git a/core/misc/dialog/dialog.ajax.js b/core/misc/dialog/dialog.ajax.js
index dd62949273..4a4794e204 100644
--- a/core/misc/dialog/dialog.ajax.js
+++ b/core/misc/dialog/dialog.ajax.js
@@ -116,8 +116,8 @@
       ).appendTo('body');
     }
     // Set up the wrapper, if there isn't one.
-    if (!ajax.wrapper) {
-      ajax.wrapper = $dialog.attr('id');
+    if (!ajax.selector) {
+      ajax.selector = `#${$dialog.attr('id')}`;
     }
 
     // Use the ajax.js insert command to populate the dialog contents.
diff --git a/core/modules/action/tests/action_form_ajax_test/src/Plugin/Action/ActionAjaxTest.php b/core/modules/action/tests/action_form_ajax_test/src/Plugin/Action/ActionAjaxTest.php
index 8afc98cf54..02075a1d28 100644
--- a/core/modules/action/tests/action_form_ajax_test/src/Plugin/Action/ActionAjaxTest.php
+++ b/core/modules/action/tests/action_form_ajax_test/src/Plugin/Action/ActionAjaxTest.php
@@ -50,7 +50,7 @@ public function buildConfigurationForm(array $form, FormStateInterface $form_sta
       '#type' => 'checkbox',
       '#title' => $this->t('Are we having a party?'),
       '#ajax' => [
-        'wrapper' => 'party-container',
+        'wrapper_selector' => '#party-container',
         'callback' => [$this, 'partyCallback'],
       ],
       '#default_value' => $having_a_party,
diff --git a/core/modules/block/src/BlockForm.php b/core/modules/block/src/BlockForm.php
index 8eb188020e..87ba3658c5 100644
--- a/core/modules/block/src/BlockForm.php
+++ b/core/modules/block/src/BlockForm.php
@@ -165,7 +165,7 @@ public function form(array $form, FormStateInterface $form_state) {
         '#default_value' => $theme,
         '#ajax' => [
           'callback' => '::themeSwitch',
-          'wrapper' => 'edit-block-region-wrapper',
+          'wrapper_selector' => '#edit-block-region-wrapper',
         ],
       ];
     }
diff --git a/core/modules/book/src/BookManager.php b/core/modules/book/src/BookManager.php
index 06dd84fdce..28f241e8b6 100644
--- a/core/modules/book/src/BookManager.php
+++ b/core/modules/book/src/BookManager.php
@@ -283,7 +283,7 @@ public function addFormElements(array $form, FormStateInterface $form_state, Nod
       '#attributes' => ['class' => ['book-title-select']],
       '#ajax' => [
         'callback' => 'book_form_update',
-        'wrapper' => 'edit-book-plid-wrapper',
+        'wrapper_selector' => '#edit-book-plid-wrapper',
         'effect' => 'fade',
         'speed' => 'fast',
       ],
diff --git a/core/modules/config/src/Form/ConfigSingleExportForm.php b/core/modules/config/src/Form/ConfigSingleExportForm.php
index c31daca71f..2d7e13315d 100644
--- a/core/modules/config/src/Form/ConfigSingleExportForm.php
+++ b/core/modules/config/src/Form/ConfigSingleExportForm.php
@@ -97,7 +97,7 @@ public function buildForm(array $form, FormStateInterface $form_state, $config_t
       '#default_value' => $config_type,
       '#ajax' => [
         'callback' => '::updateConfigurationType',
-        'wrapper' => 'js-config-form-wrapper',
+        'wrapper_selector' => '#edit-config-type-wrapper',
       ],
     ];
     $default_type = $form_state->getValue('config_type', $config_type);
@@ -110,7 +110,7 @@ public function buildForm(array $form, FormStateInterface $form_state, $config_t
       '#suffix' => '</div>',
       '#ajax' => [
         'callback' => '::updateExport',
-        'wrapper' => 'edit-export-wrapper',
+        'wrapper_selector' => '#edit-export-wrapper',
       ],
     ];
 
diff --git a/core/modules/config/tests/config_test/src/ConfigTestForm.php b/core/modules/config/tests/config_test/src/ConfigTestForm.php
index 6f1eac0b99..4127ce3d37 100644
--- a/core/modules/config/tests/config_test/src/ConfigTestForm.php
+++ b/core/modules/config/tests/config_test/src/ConfigTestForm.php
@@ -74,7 +74,7 @@ public function form(array $form, FormStateInterface $form_state) {
       '#default_value' => $size,
       '#ajax' => [
         'callback' => '::updateSize',
-        'wrapper' => 'size-wrapper',
+        'wrapper_selector' => '#size-wrapper',
       ],
     ];
     $form['size_wrapper']['size_submit'] = [
diff --git a/core/modules/editor/editor.module b/core/modules/editor/editor.module
index a4d86712fb..a77e95d53c 100644
--- a/core/modules/editor/editor.module
+++ b/core/modules/editor/editor.module
@@ -119,7 +119,7 @@ function editor_form_filter_format_form_alter(&$form, FormStateInterface $form_s
     '#ajax' => [
       'trigger_as' => ['name' => 'editor_configure'],
       'callback' => 'editor_form_filter_admin_form_ajax',
-      'wrapper' => 'editor-settings-wrapper',
+      'wrapper_selector' => '#editor-settings-wrapper',
     ],
     '#weight' => -10,
   ];
@@ -131,7 +131,7 @@ function editor_form_filter_format_form_alter(&$form, FormStateInterface $form_s
     '#submit' => ['editor_form_filter_admin_format_editor_configure'],
     '#ajax' => [
       'callback' => 'editor_form_filter_admin_form_ajax',
-      'wrapper' => 'editor-settings-wrapper',
+      'wrapper_selector' => '#editor-settings-wrapper',
     ],
     '#weight' => -10,
     '#attributes' => ['class' => ['js-hide']],
diff --git a/core/modules/field_layout/src/Form/FieldLayoutEntityDisplayFormTrait.php b/core/modules/field_layout/src/Form/FieldLayoutEntityDisplayFormTrait.php
index 170bcd093a..8e2f2e3fb4 100644
--- a/core/modules/field_layout/src/Form/FieldLayoutEntityDisplayFormTrait.php
+++ b/core/modules/field_layout/src/Form/FieldLayoutEntityDisplayFormTrait.php
@@ -65,7 +65,7 @@ public function form(array $form, FormStateInterface $form_state) {
       '#default_value' => $layout_plugin->getPluginId(),
       '#ajax' => [
         'callback' => '::settingsAjax',
-        'wrapper' => 'field-layout-settings-wrapper',
+        'wrapper_selector' => '#field-layout-settings-wrapper',
         'trigger_as' => ['name' => 'field_layout_change'],
       ],
     ];
@@ -77,7 +77,7 @@ public function form(array $form, FormStateInterface $form_state) {
       '#attributes' => ['class' => ['js-hide']],
       '#ajax' => [
         'callback' => '::settingsAjax',
-        'wrapper' => 'field-layout-settings-wrapper',
+        'wrapper_selector' => '#field-layout-settings-wrapper',
       ],
     ];
 
diff --git a/core/modules/field_ui/src/Form/EntityDisplayFormBase.php b/core/modules/field_ui/src/Form/EntityDisplayFormBase.php
index 6cc3f6bd05..6ba9446db0 100644
--- a/core/modules/field_ui/src/Form/EntityDisplayFormBase.php
+++ b/core/modules/field_ui/src/Form/EntityDisplayFormBase.php
@@ -258,7 +258,7 @@ public function form(array $form, FormStateInterface $form_state) {
       '#submit' => ['::multistepSubmit'],
       '#ajax' => [
         'callback' => '::multistepAjax',
-        'wrapper' => 'field-display-overview-wrapper',
+        'wrapper_selector' => '#field-display-overview-wrapper',
         'effect' => 'fade',
         // The button stays hidden, so we hide the Ajax spinner too. Ad-hoc
         // spinners will be added manually by the client-side script.
@@ -370,7 +370,7 @@ protected function buildFieldRow(FieldDefinitionInterface $field_definition, arr
       '#submit' => ['::multistepSubmit'],
       '#ajax' => [
         'callback' => '::multistepAjax',
-        'wrapper' => 'field-display-overview-wrapper',
+        'wrapper_selector' => '#field-display-overview-wrapper',
         'effect' => 'fade',
       ],
       '#field_name' => $field_name,
diff --git a/core/modules/file/src/Element/ManagedFile.php b/core/modules/file/src/Element/ManagedFile.php
index 8672aba730..9288b96039 100644
--- a/core/modules/file/src/Element/ManagedFile.php
+++ b/core/modules/file/src/Element/ManagedFile.php
@@ -233,7 +233,7 @@ public static function processManagedFile(&$element, FormStateInterface $form_st
           'element_parents' => implode('/', $element['#array_parents']),
         ],
       ],
-      'wrapper' => $ajax_wrapper_id,
+      'wrapper_selector' => '#' . $ajax_wrapper_id,
       'effect' => 'fade',
       'progress' => [
         'type' => $element['#progress_indicator'],
diff --git a/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php b/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
index 70bd4a7166..34c59eb429 100644
--- a/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
+++ b/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
@@ -431,11 +431,11 @@ public static function process($element, FormStateInterface $form_state, $form)
         ],
       ];
       $field_element = NestedArray::getValue($form, $parents);
-      $new_wrapper = $field_element['#id'] . '-ajax-wrapper';
+      $new_wrapper = '#' . $field_element['#id'] . '-ajax-wrapper';
       foreach (Element::children($element) as $key) {
         if (isset($element[$key]['#ajax'])) {
           $element[$key]['#ajax']['options'] = $new_options;
-          $element[$key]['#ajax']['wrapper'] = $new_wrapper;
+          $element[$key]['#ajax']['wrapper_selector'] = $new_wrapper;
         }
       }
       unset($element['#prefix'], $element['#suffix']);
diff --git a/core/modules/layout_builder/src/Form/MoveBlockForm.php b/core/modules/layout_builder/src/Form/MoveBlockForm.php
index beb3aa9757..70e23158a0 100644
--- a/core/modules/layout_builder/src/Form/MoveBlockForm.php
+++ b/core/modules/layout_builder/src/Form/MoveBlockForm.php
@@ -149,7 +149,7 @@ public function buildForm(array $form, FormStateInterface $form_state, SectionSt
       '#title' => $this->t('Region'),
       '#default_value' => "$selected_delta:$selected_region",
       '#ajax' => [
-        'wrapper' => 'layout-builder-components-table',
+        'wrapper_selector' => '#layout-builder-components-table',
         'callback' => '::getComponentsWrapper',
       ],
     ];
diff --git a/core/modules/layout_builder/src/Plugin/Block/FieldBlock.php b/core/modules/layout_builder/src/Plugin/Block/FieldBlock.php
index 1cdb92f917..c51dd9f616 100644
--- a/core/modules/layout_builder/src/Plugin/Block/FieldBlock.php
+++ b/core/modules/layout_builder/src/Plugin/Block/FieldBlock.php
@@ -267,7 +267,7 @@ public function blockForm($form, FormStateInterface $form_state) {
       '#default_value' => $config['formatter']['type'],
       '#ajax' => [
         'callback' => [static::class, 'formatterSettingsAjaxCallback'],
-        'wrapper' => 'formatter-settings-wrapper',
+        'wrapper_selector' => '#formatter-settings-wrapper',
       ],
     ];
 
diff --git a/core/modules/layout_builder/tests/modules/layout_builder_test/src/Plugin/Block/TestAjaxBlock.php b/core/modules/layout_builder/tests/modules/layout_builder_test/src/Plugin/Block/TestAjaxBlock.php
index 1f1eeb0d7f..440921b0b3 100644
--- a/core/modules/layout_builder/tests/modules/layout_builder_test/src/Plugin/Block/TestAjaxBlock.php
+++ b/core/modules/layout_builder/tests/modules/layout_builder_test/src/Plugin/Block/TestAjaxBlock.php
@@ -32,7 +32,7 @@ public function blockForm($form, FormStateInterface $form_state) {
         '@time' => time(),
       ]),
       '#ajax' => [
-        'wrapper' => 'test-ajax-wrapper',
+        'wrapper_selector' => '#test-ajax-wrapper',
         'callback' => [$this, 'ajaxCallback'],
       ],
     ];
diff --git a/core/modules/media_library/src/Form/AddFormBase.php b/core/modules/media_library/src/Form/AddFormBase.php
index 83742a3a17..149923d4a7 100644
--- a/core/modules/media_library/src/Form/AddFormBase.php
+++ b/core/modules/media_library/src/Form/AddFormBase.php
@@ -293,7 +293,7 @@ protected function buildEntityFormElement(MediaInterface $media, array $form, Fo
         ],
         '#ajax' => [
           'callback' => '::updateFormCallback',
-          'wrapper' => 'media-library-add-form-wrapper',
+          'wrapper_selector' => '#media-library-add-form-wrapper',
           'message' => $this->t('Removing @label.', ['@label' => $media->getName()]),
         ],
         '#submit' => ['::removeButtonSubmit'],
@@ -466,7 +466,7 @@ protected function buildActions(array $form, FormStateInterface $form_state) {
         '#value' => $this->t('Save'),
         '#ajax' => [
           'callback' => '::updateLibrary',
-          'wrapper' => 'media-library-add-form-wrapper',
+          'wrapper_selector' => '#media-library-add-form-wrapper',
         ],
       ],
     ];
@@ -477,7 +477,7 @@ protected function buildActions(array $form, FormStateInterface $form_state) {
         '#value' => $this->t('Save and insert'),
         '#ajax' => [
           'callback' => '::updateWidget',
-          'wrapper' => 'media-library-add-form-wrapper',
+          'wrapper_selector' => '#media-library-add-form-wrapper',
         ],
       ];
     }
@@ -588,7 +588,7 @@ public function removeButtonSubmit(array $form, FormStateInterface $form_state)
    */
   public function updateFormCallback(array &$form, FormStateInterface $form_state) {
     $triggering_element = $form_state->getTriggeringElement();
-    $wrapper_id = $triggering_element['#ajax']['wrapper'];
+    $wrapper_selector = $triggering_element['#ajax']['wrapper_selector'];
     $added_media = $form_state->get('media');
 
     $response = new AjaxResponse();
@@ -615,7 +615,7 @@ public function updateFormCallback(array &$form, FormStateInterface $form_state)
       // the next media item. If the last list item is removed, shift focus to
       // the previous item.
       else {
-        $response->addCommand(new ReplaceCommand("#$wrapper_id", $form));
+        $response->addCommand(new ReplaceCommand($wrapper_selector, $form));
 
         // Find the delta of the next media item. If there is no item with a
         // bigger delta, we automatically use the delta of the previous item and
@@ -633,7 +633,7 @@ public function updateFormCallback(array &$form, FormStateInterface $form_state)
     }
     // Update the form and shift focus to the added media items.
     else {
-      $response->addCommand(new ReplaceCommand("#$wrapper_id", $form));
+      $response->addCommand(new ReplaceCommand($wrapper_selector, $form));
       $response->addCommand(new InvokeCommand('.js-media-library-add-form-added-media', 'focus'));
     }
 
diff --git a/core/modules/media_library/src/Form/FileUploadForm.php b/core/modules/media_library/src/Form/FileUploadForm.php
index b7cbe7c6a6..a964ceb172 100644
--- a/core/modules/media_library/src/Form/FileUploadForm.php
+++ b/core/modules/media_library/src/Form/FileUploadForm.php
@@ -237,7 +237,7 @@ public function processUploadElement(array $element, FormStateInterface $form_st
     ];
     $element['upload_button']['#ajax'] = [
       'callback' => '::updateFormCallback',
-      'wrapper' => 'media-library-wrapper',
+      'wrapper_selector' => '#media-library-wrapper',
       // Add a fixed URL to post the form since AJAX forms are automatically
       // posted to <current> instead of $form['#action'].
       // @todo Remove when https://www.drupal.org/project/drupal/issues/2504115
diff --git a/core/modules/media_library/src/Form/OEmbedForm.php b/core/modules/media_library/src/Form/OEmbedForm.php
index 8b70c89691..b638800124 100644
--- a/core/modules/media_library/src/Form/OEmbedForm.php
+++ b/core/modules/media_library/src/Form/OEmbedForm.php
@@ -126,7 +126,7 @@ protected function buildInputElement(array $form, FormStateInterface $form_state
       // @todo Move validation in https://www.drupal.org/node/2988215
       '#ajax' => [
         'callback' => '::updateFormCallback',
-        'wrapper' => 'media-library-wrapper',
+        'wrapper_selector' => '#media-library-wrapper',
         // Add a fixed URL to post the form since AJAX forms are automatically
         // posted to <current> instead of $form['#action'].
         // @todo Remove when https://www.drupal.org/project/drupal/issues/2504115
diff --git a/core/modules/media_library/src/Plugin/Field/FieldWidget/MediaLibraryWidget.php b/core/modules/media_library/src/Plugin/Field/FieldWidget/MediaLibraryWidget.php
index 4bd939f753..67169175ee 100644
--- a/core/modules/media_library/src/Plugin/Field/FieldWidget/MediaLibraryWidget.php
+++ b/core/modules/media_library/src/Plugin/Field/FieldWidget/MediaLibraryWidget.php
@@ -433,7 +433,7 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
           ],
           '#ajax' => [
             'callback' => [static::class, 'updateWidget'],
-            'wrapper' => $wrapper_id,
+            'wrapper_selector' => '#' . $wrapper_id,
             'progress' => [
               'type' => 'throbber',
               'message' => $media_item->access('view label') ? $this->t('Removing @label.', ['@label' => $media_item->label()]) : $this->t('Removing media.'),
@@ -574,7 +574,7 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
       '#name' => $field_name . '-media-library-update' . $id_suffix,
       '#ajax' => [
         'callback' => [static::class, 'updateWidget'],
-        'wrapper' => $wrapper_id,
+        'wrapper_selector' => '#' . $wrapper_id,
         'progress' => [
           'type' => 'throbber',
           'message' => $this->t('Adding selection.'),
@@ -693,7 +693,7 @@ public function massageFormValues(array $values, array $form, FormStateInterface
    */
   public static function updateWidget(array $form, FormStateInterface $form_state) {
     $triggering_element = $form_state->getTriggeringElement();
-    $wrapper_id = $triggering_element['#ajax']['wrapper'];
+    $wrapper_selector = $triggering_element['#ajax']['wrapper_selector'];
 
     // This callback is either invoked from the remove button or the update
     // button, which have different nesting levels.
@@ -721,7 +721,7 @@ public static function updateWidget(array $form, FormStateInterface $form_state)
     }
 
     $response = new AjaxResponse();
-    $response->addCommand(new ReplaceCommand("#$wrapper_id", $element));
+    $response->addCommand(new ReplaceCommand($wrapper_selector, $element));
     $response->addCommand(new AnnounceCommand($announcement));
 
     // When the remove button is clicked, shift focus to the next remove button.
@@ -746,7 +746,7 @@ public static function updateWidget(array $form, FormStateInterface $form_state)
           break;
         }
       }
-      $response->addCommand(new InvokeCommand("#$wrapper_id [data-media-library-item-delta=$delta_to_focus]", 'focus'));
+      $response->addCommand(new InvokeCommand("$wrapper_selector [data-media-library-item-delta=$delta_to_focus]", 'focus'));
     }
     // Shift focus to the open button if the user removed the last selected
     // item, or when the user has added items to the selection and is allowed to
@@ -757,7 +757,7 @@ public static function updateWidget(array $form, FormStateInterface $form_state)
     // here.
     // @see Drupal.behaviors.MediaLibraryWidgetDisableButton
     elseif ($removed_last || (!$is_remove_button && !isset($element['open_button']['#attributes']['data-disabled-focus']))) {
-      $response->addCommand(new InvokeCommand("#$wrapper_id .js-media-library-open-button", 'focus'));
+      $response->addCommand(new InvokeCommand("$wrapper_selector .js-media-library-open-button", 'focus'));
     }
 
     return $response;
diff --git a/core/modules/responsive_image/src/ResponsiveImageStyleForm.php b/core/modules/responsive_image/src/ResponsiveImageStyleForm.php
index dbecba4c70..92f6d7f50d 100644
--- a/core/modules/responsive_image/src/ResponsiveImageStyleForm.php
+++ b/core/modules/responsive_image/src/ResponsiveImageStyleForm.php
@@ -101,7 +101,7 @@ public function form(array $form, FormStateInterface $form_state) {
       '#description' => $description,
       '#ajax' => [
         'callback' => '::breakpointMappingFormAjax',
-        'wrapper' => 'responsive-image-style-breakpoints-wrapper',
+        'wrapper_selector' => '#responsive-image-style-breakpoints-wrapper',
       ],
     ];
 
diff --git a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php
index 41a9b6d92a..c657399ea8 100644
--- a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php
+++ b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestAjaxElementsForm.php
@@ -39,7 +39,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#type' => 'datetime',
       '#ajax' => [
         'callback' => [$callback_object, 'datetimeCallback'],
-        'wrapper' => 'ajax_datetime_value',
+        'wrapper_selector' => '#ajax_datetime_value',
       ],
     ];
 
diff --git a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestLazyLoadForm.php b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestLazyLoadForm.php
index 7dddf877c4..e9433a49d9 100644
--- a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestLazyLoadForm.php
+++ b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestLazyLoadForm.php
@@ -37,7 +37,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#type' => 'submit',
       '#value' => $this->t('Submit'),
       '#ajax' => [
-        'wrapper' => 'ajax-forms-test-lazy-load-ajax-wrapper',
+        'wrapper_selector' => '#ajax-forms-test-lazy-load-ajax-wrapper',
         'callback' => 'ajax_forms_test_lazy_load_form_ajax',
       ],
       '#prefix' => '<div id="ajax-forms-test-lazy-load-ajax-wrapper"></div>',
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 35e0b08e20..32d8514fdc 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
@@ -86,7 +86,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
         '#title' => $this->t('AJAX checkbox in a group'),
         '#ajax' => [
           'callback' => [$object, 'checkboxGroupCallback'],
-          'wrapper' => 'checkbox-wrapper',
+          'wrapper_selector' => '#checkbox-wrapper',
         ],
       ],
       'nested_group' => [
@@ -100,7 +100,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
         '#title' => $this->t('AJAX checkbox in a nested group'),
         '#ajax' => [
           'callback' => [$object, 'checkboxGroupCallback'],
-          'wrapper' => 'checkbox-wrapper',
+          'wrapper_selector' => '#checkbox-wrapper',
         ],
       ],
     ];
diff --git a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestValidationForm.php b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestValidationForm.php
index ef6ddaf736..6f42facde6 100644
--- a/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestValidationForm.php
+++ b/core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestValidationForm.php
@@ -30,7 +30,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#default_value' => $form_state->getValue('drivertext', ''),
       '#ajax' => [
         'callback' => 'ajax_forms_test_validation_form_callback',
-        'wrapper' => 'message_area',
+        'wrapper_selector' => '#message_area',
         'method' => 'replace',
       ],
       '#suffix' => '<div id="message_area"></div>',
@@ -43,7 +43,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#default_value' => $form_state->getValue('drivernumber', ''),
       '#ajax' => [
         'callback' => 'ajax_forms_test_validation_number_form_callback',
-        'wrapper' => 'message_area_number',
+        'wrapper_selector' => '#message_area_number',
         'method' => 'replace',
       ],
       '#suffix' => '<div id="message_area_number"></div>',
diff --git a/core/modules/system/tests/modules/ajax_forms_test/src/Plugin/Block/AjaxFormBlock.php b/core/modules/system/tests/modules/ajax_forms_test/src/Plugin/Block/AjaxFormBlock.php
index 65e1372d99..3a623bde24 100644
--- a/core/modules/system/tests/modules/ajax_forms_test/src/Plugin/Block/AjaxFormBlock.php
+++ b/core/modules/system/tests/modules/ajax_forms_test/src/Plugin/Block/AjaxFormBlock.php
@@ -96,7 +96,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       ],
       '#ajax' => [
         'callback' => '::updateOptions',
-        'wrapper' => 'edit-test1-wrapper',
+        'wrapper_selector' => '#edit-test1-wrapper',
       ],
       '#prefix' => '<div id="edit-test1-wrapper">',
       '#suffix' => '</div>',
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestMachineNameValidationForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestMachineNameValidationForm.php
index 22cbb7cf45..42f31f8dba 100644
--- a/core/modules/system/tests/modules/form_test/src/Form/FormTestMachineNameValidationForm.php
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestMachineNameValidationForm.php
@@ -76,7 +76,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#required' => TRUE,
       '#ajax' => [
         'callback' => '::buildAjaxSnackConfigureForm',
-        'wrapper' => 'snack-config-form',
+        'wrapper_selector' => '#snack-config-form',
         'method' => 'replace',
         'effect' => 'fade',
       ],
diff --git a/core/modules/system/tests/modules/form_test/src/Form/FormTestTableSelectFormBase.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestTableSelectFormBase.php
index 356b1d8ab6..f719a4e171 100644
--- a/core/modules/system/tests/modules/form_test/src/Form/FormTestTableSelectFormBase.php
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestTableSelectFormBase.php
@@ -40,7 +40,7 @@ public function tableselectFormBuilder($form, FormStateInterface $form_state, $e
       '#empty' => t('Empty text.'),
       '#ajax' => [
         'callback' => 'form_test_tableselect_ajax_callback',
-        'wrapper' => 'tableselect-wrapper',
+        'wrapper_selector' => '#tableselect-wrapper',
       ],
     ];
 
diff --git a/core/modules/system/tests/modules/js_webassert_test/src/Form/JsWebAssertTestForm.php b/core/modules/system/tests/modules/js_webassert_test/src/Form/JsWebAssertTestForm.php
index 6240ec4e95..2e20094c33 100644
--- a/core/modules/system/tests/modules/js_webassert_test/src/Form/JsWebAssertTestForm.php
+++ b/core/modules/system/tests/modules/js_webassert_test/src/Form/JsWebAssertTestForm.php
@@ -38,7 +38,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
           'type' => 'throbber',
           'message' => NULL,
         ],
-        'wrapper' => 'js_webassert_test_form_wrapper',
+        'wrapper_selector' => '#js_webassert_test_form_wrapper',
       ],
     ];
     // Button to test for the waitForLink() assertion.
@@ -52,7 +52,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
           'type' => 'throbber',
           'message' => NULL,
         ],
-        'wrapper' => 'js_webassert_test_form_wrapper',
+        'wrapper_selector' => '#js_webassert_test_form_wrapper',
       ],
     ];
     // Button to test for the waitForField() assertion.
@@ -66,7 +66,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
           'type' => 'throbber',
           'message' => NULL,
         ],
-        'wrapper' => 'js_webassert_test_form_wrapper',
+        'wrapper_selector' => '#js_webassert_test_form_wrapper',
       ],
     ];
     // Button to test for the waitForId() assertion.
@@ -80,7 +80,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
           'type' => 'throbber',
           'message' => NULL,
         ],
-        'wrapper' => 'js_webassert_test_form_wrapper',
+        'wrapper_selector' => '#js_webassert_test_form_wrapper',
       ],
     ];
 
@@ -95,7 +95,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
           'type' => 'throbber',
           'message' => NULL,
         ],
-        'wrapper' => 'js_webassert_test_form_wrapper',
+        'wrapper_selector' => '#js_webassert_test_form_wrapper',
       ],
     ];
 
@@ -110,7 +110,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
           'type' => 'throbber',
           'message' => NULL,
         ],
-        'wrapper' => 'js_webassert_test_form_wrapper',
+        'wrapper_selector' => '#js_webassert_test_form_wrapper',
       ],
     ];
 
diff --git a/core/modules/views_ui/admin.inc b/core/modules/views_ui/admin.inc
index 230dd773ae..6fa7704113 100644
--- a/core/modules/views_ui/admin.inc
+++ b/core/modules/views_ui/admin.inc
@@ -54,7 +54,7 @@ function views_ui_add_ajax_trigger(&$wrapping_element, $trigger_key, $refresh_pa
   // to request so that the wrapper can be recognized by the AJAX system and
   // its content can be dynamically updated. So instead, we will keep track of
   // duplicate IDs (within a single request) on our own, later in this function.
-  $triggering_element['#ajax']['wrapper'] = 'edit-view-' . implode('-', $refresh_parents) . '-wrapper';
+  $triggering_element['#ajax']['wrapper_selector'] = '#edit-view-' . implode('-', $refresh_parents) . '-wrapper';
 
   // Add a submit button for users who do not have JavaScript enabled. It
   // should be displayed next to the triggering element on the form.
@@ -107,11 +107,11 @@ function views_ui_add_ajax_trigger(&$wrapping_element, $trigger_key, $refresh_pa
   // Attach custom data to the triggering element and submit button, so we can
   // use it in both the process function and AJAX callback.
   $ajax_data = [
-    'wrapper' => $triggering_element['#ajax']['wrapper'],
+    'wrapper_selector' => $triggering_element['#ajax']['wrapper_selector'],
     'trigger_key' => $trigger_key,
     'refresh_parents' => $refresh_parents,
   ];
-  $seen_ids[$triggering_element['#ajax']['wrapper']] = TRUE;
+  $seen_ids[$triggering_element['#ajax']['wrapper_selector']] = TRUE;
   $triggering_element['#views_ui_ajax_data'] = $ajax_data;
   $wrapping_element[$button_key]['#views_ui_ajax_data'] = $ajax_data;
 }
@@ -164,7 +164,7 @@ function views_ui_add_ajax_wrapper($element, FormStateInterface $form_state) {
 
   // The HTML ID that AJAX expects was also stored in a property on the
   // element, so use that information to insert the wrapper <div> here.
-  $id = $element['#views_ui_ajax_data']['wrapper'];
+  $id = substr($element['#views_ui_ajax_data']['wrapper_selector'], 1);
   $refresh_element += [
     '#prefix' => '',
     '#suffix' => '',
diff --git a/core/modules/views_ui/js/ajax.js b/core/modules/views_ui/js/ajax.js
index 398e6d2ed8..0f3a9369ea 100644
--- a/core/modules/views_ui/js/ajax.js
+++ b/core/modules/views_ui/js/ajax.js
@@ -251,7 +251,7 @@
           return true;
         }
 
-        elementSettings.wrapper = 'views-preview-wrapper';
+        elementSettings.wrapper_selector = '.views-preview-wrapper';
         elementSettings.method = 'replaceWith';
         elementSettings.base = link.id;
         elementSettings.element = link;
@@ -279,7 +279,7 @@
             return true;
           }
 
-          elementSettings.wrapper = 'views-preview-wrapper';
+          elementSettings.wrapper_selector = '.views-preview-wrapper';
           elementSettings.method = 'replaceWith';
           elementSettings.event = 'click';
           elementSettings.base = submit.id;
diff --git a/core/modules/views_ui/src/ViewPreviewForm.php b/core/modules/views_ui/src/ViewPreviewForm.php
index 82f93ee79a..42e482e5e7 100644
--- a/core/modules/views_ui/src/ViewPreviewForm.php
+++ b/core/modules/views_ui/src/ViewPreviewForm.php
@@ -18,7 +18,7 @@ class ViewPreviewForm extends ViewFormBase {
   public function form(array $form, FormStateInterface $form_state) {
     $view = $this->entity;
 
-    $form['#prefix'] = '<div id="views-preview-wrapper" class="views-preview-wrapper views-admin clearfix">';
+    $form['#prefix'] = '<div class="views-preview-wrapper views-admin clearfix">';
     $form['#suffix'] = '</div>';
     $form['#id'] = 'views-ui-preview-form';
 
@@ -87,7 +87,7 @@ protected function actions(array $form, FormStateInterface $form_state) {
         '#id' => 'preview-submit',
         '#ajax' => [
           'url' => Url::fromRoute('entity.view.preview_form', ['view' => $view->id(), 'display_id' => $this->displayID]),
-          'wrapper' => 'views-preview-wrapper',
+          'wrapper_selector' => '.views-preview-wrapper',
           'event' => 'click',
           'progress' => ['type' => 'fullscreen'],
           'method' => 'replaceWith',
diff --git a/core/tests/Drupal/Tests/Core/Render/Element/RenderElementTest.php b/core/tests/Drupal/Tests/Core/Render/Element/RenderElementTest.php
index be8f53c2af..df1e040b85 100644
--- a/core/tests/Drupal/Tests/Core/Render/Element/RenderElementTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/Element/RenderElementTest.php
@@ -44,33 +44,70 @@ protected function setUp(): void {
 
   /**
    * @covers ::preRenderAjaxForm
+   * @dataProvider providerTestPreRenderAjaxForm
+   *
+   * @group legacy
    */
-  public function testPreRenderAjaxForm() {
+  public function testPreRenderAjaxForm($element, $expected, $url) {
     $request = Request::create('/test');
     $request->query->set('foo', 'bar');
     $this->requestStack->push($request);
 
     $prophecy = $this->prophesize('Drupal\Core\Routing\UrlGeneratorInterface');
-    $url = '/test?foo=bar&ajax_form=1';
     $prophecy->generateFromRoute('<current>', [], ['query' => ['foo' => 'bar', FormBuilderInterface::AJAX_FORM_REQUEST => TRUE]], TRUE)
       ->willReturn((new GeneratedUrl())->setCacheContexts(['route'])->setGeneratedUrl($url));
 
     $url_generator = $prophecy->reveal();
     $this->container->set('url_generator', $url_generator);
+    $result = RenderElement::preRenderAjaxForm($element);
 
-    $element = [
-      '#type' => 'select',
-      '#id' => 'test',
-      '#ajax' => [
-        'wrapper' => 'foo',
+    $this->assertTrue($result['#ajax_processed']);
+    $this->assertSame($expected, $result['#attached']['drupalSettings']['ajax']['test']);
+  }
+
+  /**
+   * Provides test data for testPreRenderAjaxForm().
+   */
+  public function providerTestPreRenderAjaxForm() {
+    $data = [];
+    $data['wrapper_selector'] = [
+      [
+        '#type' => 'select',
+        '#id' => 'test',
+        '#ajax' => [
+          'wrapper_selector' => '#foo',
+          'callback' => 'test-callback',
+        ],
+      ],
+      [
+        'wrapper_selector' => '#foo',
         'callback' => 'test-callback',
+        'event' => 'change',
+        'url' => '/test?foo=bar&ajax_form=1',
+        'dialogType' => 'ajax',
       ],
+      '/test?foo=bar&ajax_form=1',
     ];
-
-    $element = RenderElement::preRenderAjaxForm($element);
-
-    $this->assertTrue($element['#ajax_processed']);
-    $this->assertEquals($url, $element['#attached']['drupalSettings']['ajax']['test']['url']);
+    // @todo Remove support for 'wrapper' and solely use 'wrapper_selector'.
+    $data['wrapper'] = [
+      [
+        '#type' => 'select',
+        '#id' => 'test',
+        '#ajax' => [
+          'wrapper' => 'foo',
+          'callback' => 'test-callback',
+        ],
+      ],
+      [
+        'callback' => 'test-callback',
+        'event' => 'change',
+        'wrapper_selector' => '#foo',
+        'url' => '/test?foo=bar&ajax_form=1',
+        'dialogType' => 'ajax',
+      ],
+      '/test?foo=bar&ajax_form=1',
+    ];
+    return $data;
   }
 
   /**
@@ -93,7 +130,7 @@ public function testPreRenderAjaxFormWithQueryOptions() {
       '#type' => 'select',
       '#id' => 'test',
       '#ajax' => [
-        'wrapper' => 'foo',
+        'wrapper_selector' => '#foo',
         'callback' => 'test-callback',
         'options' => [
           'query' => [