Updating To UCS 4.3 With OX App Suite Installed Results In OX Being Removed
UCS host has at least version 4.2-5e550 and OX App Suite installed.
During the update to UCS 4.3-0 the OX app gets uninstalled due to package version conflicts.
A bug has been filled and Univention is working on a fix for the issue.
As of now (January 2019) Univention has blocked the upgrade to UCS 4.3-0 for these hosts. Once the fix is published the upgrade will be possible again.
In case your OX suite already got deinstalled and you do not have a backup you might be able to continue upgrading to at least UCS 4.3-3 and then reinstall OX App Suite.