Problem
The version of rabbitmq-server in errata 1353 of UCS 4.4 has a higher version than the version present in the UCS 5.0 repositories. The version in UCS 5.0 can’t handle the newer database version of the UCS 4.4 errata which caused the upgrade to fail.
The traceback in /var/log/univention/updater.log was:
Errors were encountered while processing:
rabbitmq-server
ucs-school-celery
ucs-school-import-http-api
E: Sub-process /usr/bin/dpkg returned an error code (1)
Error: Failed to execute "apt-get -o DPkg::Options::=--force-confold -o DPkg::Options::=--force-overwrite -o DPkg::Options::=--force-overwrite-dir --trivial-only=no --assume-yes --quiet=1 -u dist-upgrade"
exitcode of univention-updater: 1
Solution
As of now, this problem will not occur anymore since the upgrade script now includes steps that stop the service and move the database to /var/lib/rabbitmq/mnesia-backup/.
The database does not store important information, at least not for the common environments.