Setup Debugging enabled and Debug messages set to DEVELOPER. Disable cron from running on the test site (that means, it shouldn't run periodically). Testing instructions Setup a course with course completion enable and a few users newly enrolled as students (annotate the id of this course because you'll need it later). Setup Course completion to allow the teacher to manually mark the user as complete within the course (Manual completion by others) Navigate to the course completion report as the teacher In lib/classes/task/completion_daily_task.php , insert a sleep(30) ; line after the get_recordset_sql() around line 87 $rs = $DB->get_recordset_sql($sql, [CONTEXT_COURSE, $now, $now]); sleep(30); // Check if result is empty. if (!$rs->valid()) { In a terminal, manually run the daily task: php admin/cli/scheduled_task.php --execute=\\core\\task\\completion_daily_task While it is sleeping, mark Approval for one of the new students in the course completion report (and annotate the id of this user because you'll need it later). Confirm that when the daily task resumes, you see something along the lines of: Exception while marking started user [USERID] in course [COURSEID] , retrying Confirm that the task completes successfully (continuing onto other users if there are more in the system), not in failure Check in the table mdl_course_completions that the record for the userid-courseid and confirm the record has a valid (non-null, non 0) timeenrolled (you'll need to replace [USERID] and [COURSEID] with the proper values): SELECT * FROM mdl_course_completions WHERE userid=[USERID] AND course=[COURSEID]