As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING LEVEL CRUISE AT FL250, CREW REPORTED THE CABIN ALTITUDE WARNING SOUNDED AND NOTICED CABIN PRESSURE APPROACHING 10K FEET. CREW COULD NOT CONTROL CABIN ALTITUDE IN STANDBY. CREW DECLARED AN EMERGENCY AND DIVERTED TO RDU. FLIGHT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED THE FORWARD OUTFLOW VALVE PER AMM 21-43-11. OPS AND LEAK CHECK GOOD.