As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 3222 - IN CRUISE FLIGHT, THE CARGO DOOR UNSAFE LIGHTS ILLUMINATED. THE CREW REDUCED THE PRESSURE DIFFERENTIAL TO ZERO AND THE LIGHT REMAINED ILLUMINATED. THE AIRCRAFT RETURNED TO MSP. MAINTENANCE ADJUSTED THE CARGO HANDLE MICROSWITCH. SYSTEM OPERATED SATISFACTORILY. (Z)