Navigate to Site administration -> Server -> Scheduled tasks Existing functionality Confirm that you see the Settings cog in the 'Edit' column Confirm that it is a link Open your config.php and set: $CFG->preventscheduledtaskchanges = false; Refresh and re-confirm Change it to: $CFG->preventscheduledtaskchanges = 0; Refresh and re-confirm Open the settings page for one of the scheduled tasks Confirm that you can see the settings page Confirm that you can make changes Prevention tests Open four copies of a task's settings page Open your config.php again and set: $CFG->preventscheduledtaskchanges = true; In one of your copies, try making a change and saving Confirm that you were redirected back to the scheduledtasks.php page and no changes were made In another copy of the page, refresh the page: Confirm that you were redirected back to the scheduledtasks.php page and no changes were made Looking at the list again: Confirm that the settings cog has been replaced by a lock Confirm that it is no longer a link Confirm it has an alt-text explaining that changes have been prevented Repeat this set of tests for $CFG->preventscheduledtaskchanges = 1;