Issue #3303557 by Binoli Lalani, quietone, catch, Tom Konda, smustgrave:...

Issue #3303557 by Binoli Lalani, quietone, catch, Tom Konda, smustgrave: Deprecate and remove the AJAX replace method

core/lib/Drupal/Core/Render/Element/RenderElementBase.php

@@ -374,6 +374,7 @@ public static function preRenderAjaxForm($element) {
 
       // @todo Legacy support. Remove in Drupal 8.
       if (isset($settings['method']) && $settings['method'] == 'replace') {
+        @trigger_error('Using "replace" as the method in #ajax property is deprecated in drupal:10.3.0 and is removed from drupal:11.0.0. Use "replaceWith" instead. See https://www.drupal.org/project/drupal/issues/3303557', E_USER_DEPRECATED);
         $settings['method'] = 'replaceWith';
       }
 

core/modules/system/tests/modules/ajax_forms_test/src/Form/AjaxFormsTestValidationForm.php

@@ -31,7 +31,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#ajax' => [
         'callback' => 'ajax_forms_test_validation_form_callback',
         'wrapper' => 'message_area',
-        'method' => 'replace',
+        'method' => 'replaceWith',
       ],
       '#suffix' => '<div id="message_area"></div>',
     ];
@@ -44,7 +44,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#ajax' => [
         'callback' => 'ajax_forms_test_validation_number_form_callback',
         'wrapper' => 'message_area_number',
-        'method' => 'replace',
+        'method' => 'replaceWith',
       ],
       '#suffix' => '<div id="message_area_number"></div>',
     ];

core/modules/system/tests/modules/form_test/src/Form/FormTestMachineNameValidationForm.php

@@ -77,7 +77,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#ajax' => [
         'callback' => '::buildAjaxSnackConfigureForm',
         'wrapper' => 'snack-config-form',
-        'method' => 'replace',
+        'method' => 'replaceWith',
         'effect' => 'fade',
       ],
     ];