Merge pull request #18571 from craftcms/bugfix/18569-failed-to-impersonate-with-token

Bugfix/18569 failed to impersonate with token

Author: brandonkelly

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Fixed an error that could occur after running the `utils/fix-field-layout-uids` command. ([#18516](https://github.com/craftcms/cms/issues/18516))
 - Fixed a JavaScript error that could occur if any field layout elements were configured with unsupported widths. ([#18552](https://github.com/craftcms/cms/issues/18552))
+- Fixed an error that could occur when user impersonation failed. ([#18569](https://github.com/craftcms/cms/issues/18569))
 
 ## 4.17.10 - 2026-03-11
 

src/controllers/UsersController.php

@@ -378,8 +378,10 @@ public function actionImpersonateWithToken(int $userId, int $prevUserId): ?Respo
         if (!$success) {
             $this->setFailFlash(Craft::t('app', 'There was a problem impersonating this user.'));
             Craft::error(sprintf('%s tried to impersonate userId: %s but something went wrong.',
-                $userSession->getIdentity()->username, $userId), __METHOD__);
-            return null;
+                $userSession->getIdentity()?->username ?? 'Unknown user', $userId), __METHOD__);
+            return $this->redirect($this->request->getIsCpRequest()
+                ? Request::CP_PATH_LOGIN
+                : Craft::$app->getConfig()->getGeneral()->getLoginPath() ?? '');
         }
 
         return $this->_handleSuccessfulLogin($user);