diff --git a/CHANGELOG-4.0.md b/CHANGELOG-4.0.md
index 734eb035cec..7ef8e131908 100644
--- a/CHANGELOG-4.0.md
+++ b/CHANGELOG-4.0.md
@@ -32,6 +32,8 @@ This file will get merged with CHANGELOG.md when releasing 4.0.0
 - `AbstractAdmin::configureActionButtons` method signature has changed
 - Moved default buttons from `AbstractAdmin::configureActionButtons` to `AbstractAdmin::getActionButtons`
 - `AbstractAdmin::getBatchActions` is now final
+- `CRUDController::handleXmlHttpRequestSuccessResponse` method is now protected
+- `CRUDController::handleXmlHttpRequestErrorResponse` method is now protected
 
 ### Removed
 - Removed BC handler for deprecated `view` `_action`
diff --git a/UPGRADE-4.0.md b/UPGRADE-4.0.md
index d543d6996af..38604776d58 100644
--- a/UPGRADE-4.0.md
+++ b/UPGRADE-4.0.md
@@ -74,3 +74,8 @@ Method `SimplePager::getResults` is always returning an array
 
 ## LockInterface
 `LockInterface` extends from `ModelManagerInterface`.
+
+## CRUDController
+The following methods changed their visiblity to protected:
+ * `handleXmlHttpRequestSuccessResponse`
+ * `handleXmlHttpRequestErrorResponse`
diff --git a/src/Controller/CRUDController.php b/src/Controller/CRUDController.php
index f591d2ca943..05e37ffb3e9 100644
--- a/src/Controller/CRUDController.php
+++ b/src/Controller/CRUDController.php
@@ -1381,6 +1381,41 @@ final protected function trans($id, array $parameters = [], $domain = null, $loc
         return $this->get('translator')->trans($id, $parameters, $domain, $locale);
     }
 
+    protected function handleXmlHttpRequestErrorResponse(Request $request, FormInterface $form): ?JsonResponse
+    {
+        if (!\in_array('application/json', $request->getAcceptableContentTypes(), true)) {
+            @trigger_error('In next major version response will return 406 NOT ACCEPTABLE without `Accept: application/json`', E_USER_DEPRECATED);
+
+            return null;
+        }
+
+        $errors = [];
+        foreach ($form->getErrors(true) as $error) {
+            $errors[] = $error->getMessage();
+        }
+
+        return $this->renderJson([
+            'result' => 'error',
+            'errors' => $errors,
+        ], Response::HTTP_BAD_REQUEST);
+    }
+
+    /**
+     * @param object $object
+     */
+    protected function handleXmlHttpRequestSuccessResponse(Request $request, $object): JsonResponse
+    {
+        if (!\in_array('application/json', $request->getAcceptableContentTypes(), true)) {
+            @trigger_error('In next major version response will return 406 NOT ACCEPTABLE without `Accept: application/json`', E_USER_DEPRECATED);
+        }
+
+        return $this->renderJson([
+            'result' => 'ok',
+            'objectId' => $this->admin->getNormalizedIdentifier($object),
+            'objectName' => $this->escapeHtml($this->admin->toString($object)),
+        ], Response::HTTP_OK);
+    }
+
     private function getSelectedTab(Request $request): array
     {
         return array_filter(['_tab' => $request->request->get('_tab')]);
@@ -1416,37 +1451,4 @@ private function setFormTheme(FormView $formView, ?array $theme = null): void
 
         $twig->getRuntime(FormRenderer::class)->setTheme($formView, $theme);
     }
-
-    private function handleXmlHttpRequestErrorResponse(Request $request, FormInterface $form): JsonResponse
-    {
-        if (!\in_array('application/json', $request->getAcceptableContentTypes(), true)) {
-            return $this->renderJson([], Response::HTTP_NOT_ACCEPTABLE);
-        }
-
-        $errors = [];
-        foreach ($form->getErrors(true) as $error) {
-            $errors[] = $error->getMessage();
-        }
-
-        return $this->renderJson([
-            'result' => 'error',
-            'errors' => $errors,
-        ], Response::HTTP_BAD_REQUEST);
-    }
-
-    /**
-     * @param object $object
-     */
-    private function handleXmlHttpRequestSuccessResponse(Request $request, $object): JsonResponse
-    {
-        if (!\in_array('application/json', $request->getAcceptableContentTypes(), true)) {
-            return $this->renderJson([], Response::HTTP_NOT_ACCEPTABLE);
-        }
-
-        return $this->renderJson([
-            'result' => 'ok',
-            'objectId' => $this->admin->getNormalizedIdentifier($object),
-            'objectName' => $this->escapeHtml($this->admin->toString($object)),
-        ], Response::HTTP_OK);
-    }
 }