diff --git a/controllers/AdminController.php b/controllers/AdminController.php
index 06b4b8b1c..6a0eb5134 100644
--- a/controllers/AdminController.php
+++ b/controllers/AdminController.php
@@ -509,7 +509,7 @@ protected function performAjaxValidation($model)
         if (\Yii::$app->request->isAjax && !\Yii::$app->request->isPjax) {
             if ($model->load(\Yii::$app->request->post())) {
                 \Yii::$app->response->format = Response::FORMAT_JSON;
-                echo json_encode(ActiveForm::validate($model));
+                return json_encode(ActiveForm::validate($model));
                 \Yii::$app->end();
             }
         }