As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ACFT DEPRESSURIZED AT 20000 FEET. ACFT DESCENDED TO 10000 FEET AND LANDED WITHOUT INCIDENT MX FOUND THE UPPER FORWARD DOOR HOOK WAS NOT LATCHING PROPERLY THAT CAUSED THE DOOR SEAL TO BLOW OUT CAUSING THE DECOMPRESSION. DOOR HOOK ADJUSTED AND THE DOOR SEAL WAS SECURED.