diff --git a/grade/grading/form/guide/classes/grades/grader/gradingpanel/external/fetch.php b/grade/grading/form/guide/classes/grades/grader/gradingpanel/external/fetch.php
index 36823725920..79d678359b2 100644
--- a/grade/grading/form/guide/classes/grades/grader/gradingpanel/external/fetch.php
+++ b/grade/grading/form/guide/classes/grades/grader/gradingpanel/external/fetch.php
@@ -156,6 +156,9 @@ class fetch extends external_api {
         $hasgrade = $gradeitem->user_has_grade($gradeduser);
         $grade = $gradeitem->get_grade_for_user($gradeduser, $USER);
         $instance = $gradeitem->get_advanced_grading_instance($USER, $grade);
+        if (!$instance) {
+            throw new moodle_exception('error:gradingunavailable', 'grading');
+        }
         $controller = $instance->get_controller();
         $definition = $controller->get_definition();
         $fillings = $instance->get_guide_filling();
diff --git a/grade/grading/form/rubric/classes/grades/grader/gradingpanel/external/fetch.php b/grade/grading/form/rubric/classes/grades/grader/gradingpanel/external/fetch.php
index 8fee77f8e8a..49fa81d21a9 100644
--- a/grade/grading/form/rubric/classes/grades/grader/gradingpanel/external/fetch.php
+++ b/grade/grading/form/rubric/classes/grades/grader/gradingpanel/external/fetch.php
@@ -149,6 +149,10 @@ class fetch extends external_api {
         $hasgrade = $gradeitem->user_has_grade($gradeduser);
         $grade = $gradeitem->get_grade_for_user($gradeduser, $USER);
         $instance = $gradeitem->get_advanced_grading_instance($USER, $grade);
+        if (!$instance) {
+            throw new moodle_exception('error:gradingunavailable', 'grading');
+        }
+
         $controller = $instance->get_controller();
         $definition = $controller->get_definition();
         $fillings = $instance->get_rubric_filling();
diff --git a/lang/en/grading.php b/lang/en/grading.php
index dd68d9100c2..68608868926 100644
--- a/lang/en/grading.php
+++ b/lang/en/grading.php
@@ -95,3 +95,4 @@ $string['templatetypeown'] = 'Own form';
 $string['templatetypeshared'] = 'Shared template';
 $string['templatesource'] = 'Location: {$a->component} ({$a->area})';
 $string['error:notinrange'] = 'Invalid grade \'{$a->grade}\' provided. Grades must be between 0 and {$a->maxgrade}.';
+$string['error:gradingunavailable'] = 'The advanced grading method is not correctly set. Please check the whole forum grading options in the forum settings.';