diff --git a/erpnext/education/doctype/assessment_result/assessment_result.js b/erpnext/education/doctype/assessment_result/assessment_result.js
index 617a873..c35f607 100644
--- a/erpnext/education/doctype/assessment_result/assessment_result.js
+++ b/erpnext/education/doctype/assessment_result/assessment_result.js
@@ -6,7 +6,8 @@
 		if (!frm.doc.__islocal) {
 			frm.trigger('setup_chart');
 		}
-		frm.set_df_property('details', 'read_only', 1);
+
+		frm.get_field('details').grid.cannot_add_rows = true;
 
 		frm.set_query('course', function() {
 			return {