Before test Tail your PHP error log. e.g. tail -f /var/log/path/to/php/error.log the path to the error log is usually in /var/log/apache2/error.log, but it may be different depending on your system. Make sure to check your PHP configuration if unsure. Test Go to Calendar Click on 'New event' Type 'Test event' in 'Event title' field. Choose todays date Select type of event 'User' Click 'Save' Click on the event we have just created on the calendar A modal should open showing title, date, time and event type ( User event ). Modify the 'eventtype' in the 'mdl_event' table directly in the database for this event and change it from 'user' to 'tool_certification1' and save it. Go to Calendar and check that you can see the event there and there is no warning. Check that there is no notice in error.log regarding tool_certification1 eventtype. Check that the 'Events key' block shows the icons for each event. Click on 'Hide global events' Check that the 'Events key' block shows the icons for each event. Click on 'Show global events' Check that the 'Events key' block shows the icons for each event.