Setup Make sure debugging is turned on. e.g. using MDK, run " mdk run mindev " Current core status Run cron a few times, ( php admin/cli/cron.php | grep legacy ) Verify that there isn't any "Use of legacy cron is deprecated" text in all the output of the cron runs. GREAT! That means that there aren't legacy uses in core. Force a legacy cron Edit mod/label/lib.php . And add these lines immediately after the <?php line: function label_cron() { echo "lalala" . PHP_EOL; return 1; } Save the file. With your favorite SQL editor, connect to the database and execute this command (the prefix "mdl_" may be different in your database): UPDATE mdl_modules SET cron = 1 where name = 'label' Run cron a few times, ( php admin/cli/cron.php ), wait more that 1 minute between runs at least once. Verify that, at very least you've got the "Use of legacy cron is deprecated" output once (it can happen more than once). Go to the zone where that output has happened. Verify that the output looks similar to this: Starting activity modules Processing module function label_cron ... lalala ++ Use of legacy cron is deprecated (label_cron). Please use scheduled tasks. ++ * line 102 of /lib/classes/task/legacy_plugin_cron_task.php: call to debugging() * line 248 of /lib/cronlib.php: call to core\task\legacy_plugin_cron_task->execute() * line 120 of /lib/cronlib.php: call to cron_run_inner_scheduled_task() * line 73 of /lib/cronlib.php: call to cron_run_scheduled_tasks() * line 79 of /admin/cli/cron.php: call to cron_run() GREAT! That means that legacy uses will be reported.