I’m not at all an expert on YunoHost, but I had a similar situation today. A failed migration from 11 to 12, also on a rented VPS.
My first attempt at migration via the web interface failed, but I couldn’t find out why exactly, because instead of the logs I recieved only 500 internal server errors.
I connected through SSH but my yunoadmin user mysteriously had been thrown out of the sudoers file, so I couldn’t do much on the command line. Fortunately I had taken a snapshot of the VPS before attempting the migration and I rolled back to that snapshot.
Now the yunoadmin could sudo again and I could attempt the migration from the command line:
sudo yunohost tools migrations run --accept-disclaimer
This went through until it failed because of a problem with grub:
Warning: E: Sub-process /usr/bin/dpkg returned an error code (1)
Warning: grub-pc: Running grub-install ...
Warning: /dev/vdb does not exist, so cannot grub-install to it!
Warning: You must correct your GRUB install devices before proceeding:
Warning:
Warning: DEBIAN_FRONTEND=dialog dpkg --configure grub-pc
Warning: dpkg --configure -a
Warning: dpkg: error processing package grub-pc (--configure):
Warning: installed grub-pc package post-installation script subprocess returned error exit status 1
Warning: Errors were encountered while processing:
Warning: grub-pc
Error: Migration 0027_migrate_to_bookworm did not complete, aborting. Error: Failed to run command 'aptitude full-upgrade --show-why -o Dpkg::Options::='--force-confold''
Info: The operation 'Run migrations' could not be completed. Please share the full log of this operation using the command 'yunohost log share 20260122-144028-tools_migrations_migrate_forward' to get help
Then I re-ran the failed command given in the error message:
sudo aptitude full-upgrade --show-why -o Dpkg::Options::='--force-confold'
This time, I ended up in an interactive dialog for grub configuration and was able to make the neccessary adjustments.
Since the migration seemed to have finished, I rebooted the server. But the UI still showed the migration as unfinished, and I couldn’t sudo anymore. It is really the migration process that messes with sudo. So I ran the migration from the UI, and while there were some warnings or even errors (I don’t remember), it completed the migration. So far, everything seems to be working as before (my first impression). And after the migration had completed, my yunoadmin user was able to sudo again.
If you still have sudo or root access to your system, perhaps you could attempt running the failed command in the last line of your log on the hastebin.
sudo aptitude full-upgrade cron rspamd- luajit- libluajit-5.1-2- --show-why -o APT::Force-LoopBreak=1 -o Dpkg::Options::='--force-confold'
Perhaps there is something that you can solve interactively, just like in my case with the grub problem.