As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RIGHT PACK HIGH PRESSURE ON CLIMB OUT AT 11000, MESSAGE DISAPPEARED, CABIN ALT WARNING MESSAGE APPEARED THEN BECAME A CABIN ALT CAUTION AS WE DESCENDED BACK THOUGH 11000. RAN THE QRH FOR CABIN ALT AND DIVERTED BACK TO DENVER. (FLIGHT 5224) OPEN.