Comment 19 for bug 1594902

Redirected here from bug 1574566,

In my case, similar to comment 4 above, I found the culpit in /var/log/syslog:

Oct 15 10:38:00 coop33695 systemd[1]: Starting Virtualization daemon...
Oct 15 10:38:00 coop33695 libvirtd[4704]: libvirt version: 1.3.1, package: 1ubuntu10.3 (Christian Ehrhar

Oct 15 10:38:00 coop33695 systemd[1]: Starting Virtualization daemon...
Oct 15 10:38:00 coop33695 libvirtd[4704]: libvirt version: 1.3.1, package: 1ubuntu10.3 (Christian Ehrhardt <email address hidden> Wed, 21 Sep 2016 13:46:44 +0200)
Oct 15 10:38:00 coop33695 libvirtd[4704]: hostname: coop33695
Oct 15 10:38:00 coop33695 libvirtd[4704]: Unable to initialize audit layer: Permission denied
Oct 15 10:38:00 coop33695 kernel: [ 1136.505334] audit: type=1400 audit(1476520680.441:81): apparmor="DENIED" operation="create" profile="/usr/sbin/libvirtd" pid=4704 comm="libvirtd" family="netlink" s
ock_type="raw" protocol=9 requested_mask="create" denied_mask="create"
Oct 15 10:38:00 coop33695 kernel: [ 1136.506987] audit: type=1400 audit(1476520680.445:82): apparmor="DENIED" operation="create" profile="/usr/sbin/libvirtd" pid=4704 comm="libvirtd" family="netlink" s
ock_type="raw" protocol=0 requested_mask="create" denied_mask="create"
Oct 15 10:38:00 coop33695 libvirtd[4704]: cannot connect to netlink socket with protocol 0: Permission denied
Oct 15 10:38:00 coop33695 systemd[1]: libvirt-bin.service: Main process exited, code=exited, status=6/NOTCONFIGURED
Oct 15 10:38:00 coop33695 systemd[1]: Failed to start Virtualization daemon.
Oct 15 10:38:00 coop33695 systemd[1]: libvirt-bin.service: Unit entered failed state.
Oct 15 10:38:00 coop33695 systemd[1]: libvirt-bin.service: Failed with result 'exit-code'.
Oct 15 10:38:00 coop33695 systemd[1]: libvirt-bin.service: Service hold-off time over, scheduling restart.
Oct 15 10:38:00 coop33695 systemd[1]: Stopped Virtualization daemon.

The suggested solution found at https://appuals.com/unable-to-initialize-audit-layer-permission-denied/ :

# sudo apparmor_parser –purge-cache
# sudo apparmor_parser -R /etc/apparmor.d/usr.sbin.libvirtd
# sudo apparmor_parser -r /etc/apparmor.d/usr.sbin.libvirtd
# sudo systemctl restart libvirt-bin
# sudo apt-get -f install

fixed my problem