Update seems to have broken scanning...

I have two computers and a Canon ImageClass 424DW multifunction scanner that are all networked via ethernet. Recently, these computers were updated to the most recent version of MacOS. Shortly thereafter, I get sporadic error messages when attempting to scan documents: "The operation couldn't be completed. (com.apple.imagecapture error 4294957375.) (-9921)". Sometimes, they scan fine. Other time, one computer will be able to scan while the other will not. And still other times, neither computer will scan. I have removed and re-added the printers/scanners. I have done full uninstalls and reinstalls with the latest drivers, and I still get these errors. Any further troubleshooting steps I can pursue? Is there any indication as to what the error message is referring to?