As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AIRCRAFT RETURNED FROM FLIGHT DUE TO ONE PRESSURE CONTROLLER ON DEVIATION AND A SECOND CONTROLLER FAILED DURING CLIMB. PASSENGER OXYGEN MASKS DEPLOYED. MAINTENANCE ACTION INVOLVED CHANGING #1 AND #2 PRESSURE CONTROLLERS AND #1 CABIN PRESSURE SELECTOR. CABIN PRESSURIZATION CHECKS CARRIED OUT.