Comment 5 for bug 1522944

It seems my system hadn't properly updated the linux-image-extra package. Everything works now after that update.

This happened after I submitted the bug report:

Start-Date: 2015-12-05 08:15:45
Commandline: /usr/bin/unattended-upgrade
Install: linux-headers-4.2.0-19:amd64 (4.2.0-19.23, automatic), linux-headers-4.
2.0-19-generic:amd64 (4.2.0-19.23, automatic), linux-image-extra-4.2.0-19-generi
c:amd64 (4.2.0-19.23, automatic)
Upgrade: linux-headers-generic:amd64 (4.2.0.18.20, 4.2.0.19.21), keepassx:amd64
(0.4.3+dfsg-0.1ubuntu1, 0.4.3+dfsg-0.1ubuntu1.15.10.1), thunderbird-locale-en-us
:amd64 (38.3.0+build1-0ubuntu2, 38.4.0+build3-0ubuntu0.15.10.1), thunderbird:amd
64 (38.3.0+build1-0ubuntu2, 38.4.0+build3-0ubuntu0.15.10.1), thunderbird-locale-
en:amd64 (38.3.0+build1-0ubuntu2, 38.4.0+build3-0ubuntu0.15.10.1), thunderbird-locale-fi:amd64 (38.3.0+build1-0ubuntu2, 38.4.0+build3-0ubuntu0.15.10.1), thunderbird-gnome-support:amd64 (38.3.0+build1-0ubuntu2, 38.4.0+build3-0ubuntu0.15.10.1), linux-libc-dev:amd64 (4.2.0-18.22, 4.2.0-19.23), linux-image-generic:amd64 (4.2.0.18.20, 4.2.0.19.21), linux-generic:amd64 (4.2.0.18.20, 4.2.0.19.21)

I had some problems related to the hplip package so I had to do apt-get -f install:

Start-Date: 2015-12-08 15:08:27
Commandline: apt-get -f install
Upgrade: linux-image-extra-4.2.0-19-generic:amd64 (4.2.0-19.23, 4.2.0-19.23)
Remove: hplip:amd64 (3.15.11-0ubuntu1), printer-driver-postscript-hp:amd64 (3.15.7-0ubuntu4), hplip-gui:amd64 (3.15.7-0ubuntu4)
End-Date: 2015-12-08 15:09:15

I think this finally resolved the problem.