I copy some answers from this page:
Post number 13:
I just received some updates:
libudev1 (229-4ubuntu5) to 229-4ubuntu6
libudev1:i386 (229-4ubuntu5) to 229-4ubuntu6
python3-urllib3 (1.13.1-2) to 1.13.1-2ubuntu0.16.04.1
systemd (229-4ubuntu5) to 229-4ubuntu6
systemd-sysv (229-4ubuntu5) to 229-4ubuntu6
udev (229-4ubuntu5) to 229-4ubuntu6
Xsane just works fine now (without any configuration). It might be
that the two extra config-files in /etc/systemd/system (saned.socket
and saned@.service) are still needed. So I will do some more testing
before celebrating :)
And post number 18:
While the systemd related updates fixed sane again as I could find the
pixma scanner again... However, it turned out to be a scanner from the
office downstairs (lol, saves me some electricity but I am not sure
whether they would be happy with that ;) ).
To find my own scanner (pixma MG5700 series) I had to upgrade to
sane-backends-1.0.26 (from 1.0.25). I added a ppa to my sources.list
to do this the easy way:
deb http://ppa.launchpad.net/rolfbensch/sane-git/ubuntu xenial main
This version works like a charm.
Anyway, I am clueless about what the systemd fixed but it did it.
It might be useful to read all the posts because that will explain why I initially added saned.socket to /etc/systemd/system but this is no longer needed.