Put Moodle into Dev mode and update composer dependencies: mdk run dev php composer.phar install Open lib/classes/userfeedback.php in your preferred editor Locate the can_give_feedback() method and add into the body of the method: debugging('This method is deprecated!'); Log into Moodle and navigate to the Dashboard Confirm that you see a pretty Whoops page Remove the vendor directory rm -rf vendor Refresh the page Confirm that you get a regular text-based debugging mesage as a part of the page Open config.php in your preferred editor Somewhere before the require_once line, add: $CFG->debug_developer_debugging_as_error = true; Refresh the page Confirm that you get some kind of notice Note: If you are using xdebug, it will be butt ugly and Orange Change the setting to false: $CFG->debug_developer_debugging_as_error = false; Refresh the page Confirm that you get a debugging notice with stack trace Install composer dependencies again; php composer.phar install Refresh the page Confirm that you get a debugging notice with stack trace (not whoops) Unset the setting (remove it) Refresh the page Confirm that you get a pretty Whoops page Run mdk undev: mdk run undev Refresh the page Confirm you got nothing