For anyone finding this after the fact. I had to remove dpkg-fsys-usrunmess.
Use aptitude because apt's crap resolver won't do it. aptitude --allow-remove-essential install usrmerge aptitude remove dpkg-fsys-usrunmess Then I manually (with a script) had to delete a bunch of duplicated files, because I had older files in /lib and newer ones in /usr/lib. This is the script, don't run it blindly while /usr/lib/usrmerge/convert-usrmerge 2>&1 | grep Both | cut -d\ -fusrmerge; do /usr/lib/usrmerge/convert-usrmerge 2>&1 | grep Both | cut -d\ -f 4 rm $(/usr/lib/usrmerge /convert-usrmerge 2>&1 | grep Both | cut -d\ -f 4) done After this, I could run again aptitude install usrmerge After this, the system seems in an upgradable state again. -- Salvo Tomaselli "Io non mi sento obbligato a credere che lo stesso Dio che ci ha dotato di senso, ragione ed intelletto intendesse che noi ne facessimo a meno." -- Galileo Galilei https://ltworf.github.io/