As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FORTY-FIVE MINUTES OUT OF DCA, THE CREW RECEIVED A CABIN ALTITUDE PRESSURE WARNING INDICATION. THE PRESSURIZATION WAS UNCONTROLLABLE. THE CREW DECLARED AN EMERGENCY, FOLLOWED THE QUICK REFERENCE HANDBOOK, AND DESCENDED TO 10,000 FEET. THE CREW SWITCHED TO MANUAL MODE AND CONTINUED ON TO DCA WITH NO FURTHER INCIDENTS. MAINTENANCE INSPECTED AND DEFERRED THE AUTO MODE PRESSURIZATION.