As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER TAKEOFF, AN OPEN DOOR PASSENGER DOOR WARNING MESSAGE APPEARED. THE AIRCRAFT RETURNED TO OTTAWA. AFTER LANDING, THEY FOUND THAT THE OUTER HANDLE WAS POPPED OUT. THE INNER HANDLE STOP WAS ADJUSTED. THE INNER DOOR RIGGING CHECK OK, PASSENGER DOOR SENSORS S26 AND S27 ADJUSTED AS PER MAINTENANCE MANUAL.