As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN WOULD NOT PRESSURIZE IN EITHER AUTO OR MANUAL AFTER TAKEOFF. FLIGHT RETURNED TO DTW AND LANDED WITHOUT INCIDENT. INSPECTED ALL DOOR SEALS, OUTFLOW VALVE, AND PRESSURIZED AIRCRAFT WITH BOTH ENGINES RUNNING. ALL CHECKED OK WITH NO PROBLEMS FOUND. AIRCRAFT RETURNED TO SERVICE.