--- a/backup/util/helper/backup_cron_helper.class.php
+++ b/backup/util/helper/backup_cron_helper.class.php
@@ -740,6 +740,8 @@ abstract class backup_cron_automated_helper {
                 $where .= " and target <> 'course_backup'";
             }
 
+            $where.=" and (target <> 'calendar_event' or crud='c')";
+
             if ($reader->get_events_select_count($where, $params)) {
                 return true;
             }