As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT WAS DIVERTED WHEN DURING THE CLIMB, THE CREW RECEIVED A CABIN PRESSURE MASTER WARNING. THE CHECK LISTS WERE COMPLIED WITH BUT THE CREW WAS UNABLE TO CONTROL THE PRESSURIZATION. MAINTENANCE INSPECTED THE AIRCRAFT AND REPLACED THE AFT CARGO DOOR SEAL. OPERATIONAL CHECKS WERE GOOD AND THE AIRCRAFT WAS RETURNED TO SERVICE.