As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AT FLIGHT LEVEL 22000, CABIN LOST PRESSURE. AN EMERGENCY DESCENT WAS CARRIED OUT AND THE REMAINDER OF THE FLIGHT WAS NORMAL. UPON INSPECTION THE OUTFLOW VALVE WAS FOUND TO BE LOOSE AND DIRTY. THE VALVE WAS CLEANED & TIGHTENED, THEN A SATISFACTORY TEST FLIGHT WAS CARRIED OUT.