An UCS c’t edition with UCS version 3.2-4 cannot update to UCS 4.0 because:
“The update to UCS 4.0 is blocked because the component ‘ucs-ct-edition’ is marked as required.”
UCS updates require current versions of all installed apps/components - for the component ucs-ct-edition no newer component is available, because all contents were integrated in UCS itself.
Therefore you can simply deactivate the old component and remove the old meta package - all these steps can either be achieved at shell or UMC. This article documents the shell way.
1. Deactivate the component
ucr set repository/online/component/ucs-ct-edition=no
2. Remove the old meta package
apt-get purge ucs-ct-edition
3. Upgrade to UCS 4.0