As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE AT FL 235, CABIN ALTITUDE KEPT CLIMBING TO 9550 FEET INLET, EXTRACT AND OUTFLOW VALVES ALL FULLY CLOSED. CABIN DIFFERENTIAL WAS 4.2 PSI. UNABLE TO MAINTANIN CABIN PRESSURIZATION UNTIL DESCENDING. DECLARED EMERGENCY AND LANDED WITHOUT ISSUE. MAINTENANCE FOUND FORWARD CARGO DOOR SEAL AT TOP LEFT CORNER DEFORMED AND NOT SEALING PROPERLY. REPLACED FORWARD CARGO DOOR SEAL IAW MM 52-31-18. AIRCRAFT WAS GROUNDED.