we had a problem yesterday with running univention-upgrade.
Specifically, the upgrade failed, because dovecot could not be stopped on that machine. After digging a little bit I realized, that additionally to dovecot.service a dovecot.socket exists, which starts dovecot once one of the ports is accessed. This one had to be stopped with systemctl stop dovecot.socket.
This configuration does not seem to yield advantages, as a stopping dovecot hints at some severe problem and restarting it because the port is accessed will not make it better.
Restarting the upgrade afterwards did not show any updates, the shown errata level was 329. I had to manually run apt-get -f install to finish the process, now univention-upgrade also shows the correct errata level. The system also had to be rebooted otherwise a login to nagios was not possible.
Is this behaviour known?