As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5723, SDF TO IAH. ACFT WOULD NOT PRESSURIZE PROPERLY DURING CLIMB. CABIN ALTITUDE CLIMBED EXCESSIVELY AND CREW RECEIVED CABIN MESSAGE. THE FLIGHT RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT THE FAULT TO THE AUTO PRESSURE CONTROLLER. AFTER REPLACEMENT THE PRESSURIZATION SYSTEM OPERATED NORMALLY. (S)