As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED A CABIN ALTITUDE CAUTION MESSAGE ON CLIMBOUT OF CLT. CREW ELECTED TO RETURN TO CLT AND LANDED WITHOUT INCIDENT. MAINTENANCE PERFORMED OPERATIONAL CHECKS OF THE PRESSURIZATION SYSTEM. MAINTENANCE REMOVED AND REPLACED THE PRIMARY OUTFLOW VALVE IN ACCORDANCE WITH THE AIRCRAFT MAINTENANCE MANUAL. AIRCRAFT WAS RELEASED FOR SERVICE.