As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF AT 9,500 THE MAIN CARGO DOOR LIGHT ILLUMINATED. DID THE QRH & RETURNED TO DEPARTURE. DUPLICATED DEFECT BY PRESSURIZING ACFT. FOUND MAIN DOOR HOOK LATCH INDICATOR SWITCH OUT OF ADJUSTMENT. CORRECTED INDICATOR SWITCH ADJUSTMENT IAW MM 52-71-09. OPS CHECKED GOOD.