As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT FROM BOS RECEIVED "CABIN PRESSURE ALT MSG". A/C RETURNED TO BOS LANDED SAFELY. INSPECTED A/C FOUND CARGO DOOR AJAR WITH NET CAUGHT IN DOOR TRACK. REPOSITIONED NET AND SECURED CARGO DOOR CLOSED. OPS CHECK OF PRESSURIZATION GOOD.