As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DIVERSION / DECLARED EMERGENCY. CABIN ALTITUDE WARNING HORN ACTIVATED AT FL 340 WHOLE IN CRUISE. CABIN ALTITUDE REACHED 10,000 FEET. OXYGEN MASKS NEVER DROPPED DUE TO AN IMMEDIATE EMERGENCY DESCENT DOWN TO 10,000 FEET MSL. REMOVED AND REPLACED OUTFLOW VALVE PER MM.