Problem:
You are in a conflictiong situation, that you are updateing from UCS-5.0-10 to 5.2, and stuck with the disk_space check from the preupdate in version 5.1
You have a new kernel, and the running one.
If you check to remove one of the kernals you see, that univention-server-master will be removed as well.
So you have one more option:
Solution:
Rebuild the kernel with only the necessary hardware modules
ucr info initramfs/modules
initramfs/modules: most
Configures which kernel modules should be integrated into the initrd. If the variable is set to 'most', most filesystem and all and hard drive modules are integrated; 'netboot' only adds base modules and network drivers, 'dep' performs automatic detection of the modules which are to be integrated and 'list' only loads the modules explictly listed in `/etc/initramfs-tools/modules{,.d/*}`. If the variable is unset, 'most' applies.
Categories: system-base
Default: most
Type: str
You can set this variable to dep , means that automatically will check for the necessary modules needed for the hardware
ucr set initramfs/modules='dep'
dpkg-reconfigure linux-image-5.10.0-30-amd64
You will receive more diskspace at boot and can proceed with the update.
If you are on the expected version, you can set the variable to ‘most’ again, and do the reconfiguration on the new kernel. If this kernel is selected during reboot, it has all modules again.
Addition:
Also nice for the update:
ucr set update50/pruneoldkernel=yes
ucr set update51/pruneoldkernel=yes
ucr set update52/pruneoldkernel=yes
univention-prune-kernels