Problem
The listener seems not to be up and running. It appears to be out of sync. Nagios reports errors as follows:
UNIVENTION_REPLICATION
CRITICAL 2018-12-04 09:49:20 0d 1h 10m 38s 5/5 CRITICAL: no change of listener transaction id for last 10 checks (nid=240976 lid=cat: /var/lib/univention-directory-listener/notifier_id: No such file or directory)
Investigation
In /var/log/univention/listener.log you might see entries like this:
04.12.18 08:48:47.597 LISTENER ( ERROR ) : import of filename=/usr/lib/univention-directory-listener/system/company_name-offboarding.py failed
You have configured an additional listener module which appears to fail for some reason so the listener does not start correctly.
Solution
Option 1
Remove your failing listener module and restart the listener:
systemctl start univention-directory-listener
Option 2
Perform troubleshooting why it fails.