As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) UPON ARRIVAL THE FLIGHT CREW COULD NOT OPEN THE MAIN CABIN DOOR. THE MECHANISM INSIDE THE DOOR WAS FROZEN, SO THE DOOR HANDLE COULD NOT BE TURNED FROM THE INSIDE. A PERSON STANDING OUTSIDE THE AIRCRAFT HAD TO OPERATE THE OUTER DOOR HANDLE IN TANDEM WITH THE CREW TURNING THE DOOR HANDLE ON THE INSIDE OF THE DOOR. EVENTUALLY THE LINKAGE WAS FREED UP AND THE DOOR OPENED.