As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL340, RECEIVED L2 PASSENGER AFT OPEN ON EICAS. LOOKED AT MFD AND SAW RED INDICATION ON L2 DOOR. FOLLOWED QRH AND FOUND DOOR CLOSED, LOCKED, AND LATCHED. CONTINUED FLIGHT. MESSAGE WENT AWAY AT FL220. DOOR INDICATIONS NORMAL. INSPECTED L2 DOOR AND FOUND NO OBVIOUS DEFECTS. PERFORMED PROXIMITY SENSOR TEST FIM 52-70-00 AND OPS CHECK GOOD. ARMED AND DISARMED INDICATIONS NORMAL.