As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN ALTITUDE WARNING LIGHT WITH EICAS ON AT FLT390. DIVERTED WITH AN EMERGENCY DECLARATION. LANDED WITHOUT INCIDENT. REMOVED AND REPLACED THE CABIN PRESSURE CONTROLLER. LEAK AND OPS CHECKED SATISFACTORY. COMPLIED WITH CONDITIONAL INSPECTION 05-51-24. FAULT NOT DUPLICATED. AIRCRAFT RELEASED TO SERVICE.