As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) GEAR DISAGREE MSG ON GEAR DOWN SELECTION, MAINS INDICATING GREEN AND THE NOSE INDICATING WHITE. CREW CYCLED GEAR WITH SAME RESULT. THEY THEN DID AN ALTERNATE EXTENSION AND GOT THE 3 GREEN INDICATION AND LANDED WITH NO PROBLEM. (LANDING GEAR RETRACTION SYSTEM) MX T/S REVEALED THE NLG DOOR SELECTOR VALVE TO BE AT FAULT. THE SELECTOR VALVE WAS REPLACED AND GEAR SWINGS WERE C/O AND THE ACFT WAS CHECKED SERVICEABLE.