As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GEAR DISAGREE WARNING MESSAGE AFTER T/O RT MAIN GEAR SHOWED A RED BOX COMPLIED WITH QRH AND GEAR CAME DOWN WITH ALTERNATE EXTENSION PROCEDURE. (ACFT RETURNED TO DEPARTURE, EMERGENCY DECLARED. FOUND RT MAIN UPLOCK PROXIMITY SENSOR GAP OUT OF ADJUSTMENT. ADJUSTED RT MAIN UPLOCK PROXIMITY SENSOR TO SPEC IAW AMM 32-32-05. OPS TESTED GOOD. NO DEFECTS NOTED.