The scanner is in use by application '(null)' Until now I've always scanned through the Printers &amp; Scanners part of options. It's far from great so now I want to try scanning through Preview. Now I get this error message: The scanner is in use by application '(null)'.

And I get it both from Preview as well as the stuff I used before.





Is there a good way to fix this? I.e. without rebooting.
I encountered the same question on my MacBook Pro.  I solved it by changing to another USB  port; I didn't have to restart.