As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
KMIA - AFTER DEPARTURE DURING CLIMB STAGE, UNABLE TO OBTAIN CABIN PRESSURE. DUMPED FUEL AND RETURNED TO KMIA LANDING UNEVENTFULLY. FOUND LOOSE ELECTRICAL CONNECTOR AT THE PNEUMATIC FLOW CONTROL/SHUT-OFF VALVE, P/N 39608831. TIGHTENED THE CONNECTOR, OPERATIONAL TEST NORMAL PER MM21-30-00 P501-P503. RETURNED TO SERVICE.