diff --git a/typo3/sysext/backend/Classes/Controller/FileSystemNavigationFrameController.php b/typo3/sysext/backend/Classes/Controller/FileSystemNavigationFrameController.php
index 260da27c501eaeb1b509afb0254116d5b7d6e9e4..85eab22c35efabe8bf3e7453aa3dafb4913d71bf 100644
--- a/typo3/sysext/backend/Classes/Controller/FileSystemNavigationFrameController.php
+++ b/typo3/sysext/backend/Classes/Controller/FileSystemNavigationFrameController.php
@@ -236,7 +236,7 @@ class FileSystemNavigationFrameController
         if ($this->foldertree->getAjaxStatus() === false) {
             return $response->withStatus(500);
         }
-        return GeneralUtility::makeInstance(JsonResponse::class, $tree);
+        return GeneralUtility::makeInstance(JsonResponse::class, [$tree]);
     }
 
     /**