Comment 2 for bug 1542033

Same here. Just upgraded from 14.04.5 to 16.04.1
Apparmor forbids avahi to create datagram socket, so it dies with an assertion:
$ journalctl -ab0 | grep avahi
авг 30 11:51:46 amanda audit[2230]: AVC apparmor="STATUS" operation="profile_load" profile="unconfined" name="/usr/sbin/avahi-daemon" pid=2230 comm="apparmor_parser"
авг 30 11:51:48 amanda avahi-daemon[2368]: Found user 'avahi' (UID 114) and group 'avahi' (GID 121).
авг 30 11:51:48 amanda avahi-daemon[2368]: Successfully dropped root privileges.
авг 30 11:51:48 amanda avahi-daemon[2368]: avahi-daemon 0.6.32-rc starting up.
авг 30 11:51:48 amanda audit[2368]: AVC apparmor="DENIED" operation="sendmsg" profile="/usr/sbin/avahi-daemon" name="/run/systemd/notify" pid=2368 comm="avahi-daemon" requested_mask="w" denied_mask="w" fsuid=114 ouid=0
авг 30 11:51:48 amanda avahi-daemon[2368]: Successfully called chroot().
авг 30 11:51:48 amanda avahi-daemon[2368]: Successfully dropped remaining capabilities.
авг 30 11:51:48 amanda avahi-daemon[2368]: No service file found in /etc/avahi/services.
авг 30 11:51:48 amanda audit[2368]: AVC apparmor="DENIED" operation="create" profile="/usr/sbin/avahi-daemon" pid=2368 comm="avahi-daemon" family="netlink" sock_type="dgram" protocol=0 requested_mask="create" denied_mask="create"
авг 30 11:51:48 amanda avahi-daemon[2368]: on: starting up: iface-linux.c:380: avahi_interface_monitor_sync: Assertion `m' failed.
авг 30 11:51:48 amanda avahi-daemon[2368]: netlink.c: socket(PF_NETLINK): Permission denied
авг 30 11:51:48 amanda systemd[1]: avahi-daemon.service: Main process exited, code=killed, status=6/ABRT
авг 30 11:51:48 amanda systemd[1]: avahi-daemon.service: Unit entered failed state.
авг 30 11:51:48 amanda systemd[1]: avahi-daemon.service: Failed with result 'signal'.