Brother network scanner stopped working after 20.04 update

I have DCP-1610W which used to work just fine using Simple Scan before upgrading from 18.04 to 20.04.

brscan-skey seems to think it's fine

➜ brscan-skey -l
DCP-1610W         : brother4:net1;dev0  : 192.168.2.184        Active

brsaneconfig4 as well

➜ brsaneconfig4 -q
...
Devices on network
  0 DCP-1610W           "DCP-1610W"         I:192.168.2.184

and it looks like all the drivers are up to date

➜ dpkg -l | grep Brother
ii  brother-udev-rule-type1                    1.0.2                                      all          Brother udev rule type 1
ii  brscan-skey                                0.2.4-1                                    amd64        Brother Linux scanner S-KEY tool
ii  brscan4                                    0.4.5-1                                    amd64        Brother Scanner Driver
ii  dcp1610wcupswrapper:i386                   3.0.1-1                                    i386         Brother DCP-1610W CUPS wrapper driver
ii  dcp1610wlpr:i386                           3.0.1-1                                    i386         Brother DCP-1610W LPR driver
ii  printer-driver-brlaser                     6-1build1                                  amd64        printer driver for (some) Brother laser printers
ii  printer-driver-ptouch                      1.4.2-3                                    amd64        printer driver Brother P-touch label printers

It's just that Simple Scan (now Document Scanner) says No scanners detected after a brief search.

All the similar posts suggest the fixes which I have already had to apply to get the scanner working in 18.04, like making sure that the drivers found in /usr/lib64/sane/ are also available under /usr/lib/sane

Solution 1:

Found it.

List of sane backends in /etc/sane.d/dll.conf got moved to /etc/sane.d/dll.conf.dpkg-old during upgrade, and the "new" one didn't contain brother4 backend.

I've added it and now the scanner gets found by frontends.