As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: SMOKE LAVATORY EICAS MESSAGE ON DURING DESCENT. ALARM ORIGINATED AT LAVATORY 3F-1LC. FLIGHT ATTENDANTS ADVISE NO SMOKE PRESENT. ACCOMPLISHED FIM TASK 26-10-F3-46A-421A. NO FAULTS PRESENT. ACCOMPLISHED SATISFACTORY OPERATIONAL TEST.