As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: DURING CRUISE WE NOTICED APU AGENT DISCHARGE LIGHT ILLUMINATED. DURING DESCENT THE LIGHT EXTINGUISHED. MAINTENANCE PERFORMED AN OPERATIONAL TEST OF APU FIRE EXTINGUISHING LOOP/SQUIB PER AMM 26-22-00 WITH NO FAULTS NOTED.