The Univention Mangement Console (UMC) will offer you the update to a set target version (see UCS Handbook). This usually installs all needed software updates without any user interactions needed.
When updating UCS systems with UCS@school from UCS 4.4-9 to UCS 5.0-2, the update will stop with an error in UCS versions 5.0-0 until 5.0-1 errata 223 and you must explicitly trigger the UCS@school update in the Univention App Center before you can continue the UCS update.
Technical details
UCS 5.0-2 can not be installed while UCS@school 5.0 v1 is still present. This restriction has been put into place due to an update in UCS 5.0-2 which is incompatible with UCS@school 5.0 v1. So UCS@school has to be updated to 5.0 v2 first. This is logged in /var/log/univention/updater.log, but there is no message in the UMC. After upgrading UCS@school, the update to UCS 5.0-2 can continue among the updates provided by UCS@school.
We recommend to run the update via the command line with the command univention-upgrade.
This way, you are told everything you need to know and do by the Univention App Center mechanisms. If you already run your updates this way, you don’t need to change anything. Before starting any update, make sure to visit the UCS@school 5.0 Release Notes as well as the UCS@school 5.0 v2 Changelog. The ‘UMC-way’ of updating still works, but is less verbose.
You can also run the update with the following commands to avoid the described error messages:
$ univention-upgrade --ignoressh --ignoreterm --noninteractive --updateto=5.0-0 --disable-app-updates
$ univention-app upgrade ucsschool
$ univention-upgrade --ignoressh --ignoreterm --noninteractive