As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, THE CREW RECEIVED A LANDING GEAR LEVER DISAGREE WARNING MESSAGE. AFTER PERFORMING THE QRH PROCEDURES, THE MESSAGE DID NOT CLEAR. THE CREW DECIDED TO MAKE AN UNSCHEDULED LANDING WHICH WAS SUCCESSFULLY COMPLETED. MAINTENANCE THEN FOUND AN INOPERATIVE RT MLG UPLOCK BOX AND REPLACED THE ASSEMBLY. ALL OPS CHECKS WERE GOOD AND THERE HAVE BEEN NO FURTHER FAULTS.