As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER TAKEOFF WHEN THE GEAR WAS RETRACTED, THE LEFT MAIN GEAR DOOR LIGHT ON THE ENGINEERS PANEL AND THE DOOR UNSAFE LIGHT REMAINED ILLUMINATED. THE CREW CYCLED THE GEAR AND THE LIGHT REMAINED ON, THE CREW ELECTED TO RETURN TO THE POINT OF ORIGIN. THE SWITCH AND CONNECTOR WERE REPLACED AND THE AIRCRAFT DEPARTED.