Avahi Daemon fails on start-up

[skra72]

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Describe the bug / Actual behaviour:
[[A clear and concise description of what the bug is.]]
The Avahi-Bonjour-daemon often fails to start when booting.

The log shows the following error:

avahi-daemon[711]: dbus_bus_get_private(): Failed to connect to socket /var/run/dbus/system_bus_socket: No such file or directory

Expected behaviour:
Avahi daemon should always start on booting.

Has this issue started to happen just recently?
Since the upgrade from 6.4 to 7.4.

If yes, roughly when did it last work fine for you?
Version 6.4

To reproduce:
Steps to reproduce the behavior:
Reboot

Image/Box Model (please complete the following information):

• Version: 7.4
• BoxModel: Formuler F1

Additional context
Seems to be a race condition / timing issue as the DBUS socket takes longer to be available than Avahi to start-up. However, avahi daemon already has a boot dependency to DBUS.

Interesting is that when enabling debug-logging the problem never happens.

Current workaround is to add a @reboot crontab rule to restart avahi.