What was found
APPROXIMATELY 1.5 - 2 HOURS INTO FLIGHT AT FL450, WE RECEIVED THE AMBER CHECK DOORS AND CABIN DOOR OPEN MESSAGES IN CRUISE. WE COMPLIED WITH THE APPROPRIATE QRH PROCEDURES AND ASSOCIATED RESTRICTIONS. FODM AND MX WERE CONSULTED AND A DIVERSION WAS INITIATED. UPON LANDING, THE AMBER DOOR OPEN LIGHT NEXT TO THE CABIN DOOR HANDLE WAS ILLUMINATED. WHEN THE RED HANDLE UNLOCK BUTTON WAS DEPRESSED, THE AUDIBLE CLICK OF THE LOCKING PAW COULD BE HEARD. CORRECTIVE ACTION: REPLACED PCB, MAIN DOOR PADDLE HANDLE CORD SET, AND PROX SWITCH. OPS CHECK GOOD. IAW AMM 52-70-00, 52-70-10, 52-10-50, 24-60-40.