As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED RECEIVING A RED CABIN ALT MESSAGE CLIMBING THROUGH 11,000 FT. THE CREW FOLLOWED EMERGENCY PROCEDURES AND RETURNED TO FIELD WITHOUT FURTHER INCIDENT. MAINTENANCE INSPECTED, SEATED THE CARGO BAY DOOR AND PERFORMED CHECKS IAW THE AMM. THE ACFT WAS RELEASED FOR SERVICE.