diff --git a/grade/edit/tree/grade.php b/grade/edit/tree/grade.php
index 2ccbc3b28c3..0c746bcd8ed 100644
--- a/grade/edit/tree/grade.php
+++ b/grade/edit/tree/grade.php
@@ -168,7 +168,7 @@ if ($mform->is_cancelled()) {
 
     if (isset($data->feedback) && is_array($data->feedback)) {
         $data->feedbackformat = $data->feedback['format'];
-        $data->feedback = $data->feedback['text'];
+        $data->feedback = $data->feedback['text'] ?? null;
     }
 
     $old_grade_grade = new grade_grade(array('userid'=>$data->userid, 'itemid'=>$grade_item->id), true); //might not exist yet