As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEVEL AT FL 340 OVER LONDON AEROSPACE, WE GOT A DOOR L AFT CABIN ECAM MESSAGE, CLEARED THE ECAM AND FOLLOWED QRH. THE LEFT AFT DOOR INDICATOR SHOWED 1/2 GREEN AND 1/2 RED AND ARMED NO INCREASE IN CABIN ALTITUDE OR V/S. CABIN ALTITUDE STEADY AT 5350'. RIGGED 4L DOOR LOCKING MECHANISM. R/R PROX SWITCH (25MJ) ON 4L DOOR. PRESSURIZED AIRCRAFT NO ISSUES NOTED.