If the wrist stops operating properly and displays a runtime error, the wrist has disconnected during operation. Check LED status lights for each wrist motor, noting any red flashing lights.
Check all wires and ensure that each has a secure connection. You will need to remove the wrist and covers to access some of the connection points:
Check both ends of cable #21
Check both ends of cable #22
Check both ends of cable #23
If all cables look connected, but you are still receiving this error, carefully disconnect and reconnect each cable; Firmly pressing each one to ensure that it's all the way seated.
Move the arm to extended/off position, power down, and restart the robot.