MG6350 Prints but can't open scanner "failed to open ... device (-21345) Sonama OS on iMac

[RobinWhalley]

I can print OK but using a wired USB connection from my iMac to the Canon MG6350 but I can't open a scanner window. I get the "failed to open a connection to the device (-21345) message.    Software Sonama OS 14.3.1