I think this is a timeout error. I came across it recently and ended up changing the Lightning/USB cable.
I tried several times to restore a phone with the original cable. First time with the new cable was successful. Rebooting the computer and updating software/OS may also help.
Try a different cable and port. Update the drivers also. If all else fails, look up how to uninstall itunes and follow the order of uninstallation. Re install it and you should be good to go.