"Error processing package" - apt upgrade cannot run due to package configuration errors
Solution 1:
With
stat / /dev /var
check if you are the owner of all directories. If not, run:
chown root DirectoryYouAreNotOwner
In my case, the owner of / was Unknown. So I used the command:
chown root /
Solution 2:
The answer of Miguel Saldanha did not work for me and I tried searching a bit more. Finally, the answer from this post helped me. Just posting the answer here because this has been referred in several places and in case someone needs it in future.
sudo rm /var/lib/dpkg/info/systemd*
sudo dpkg --configure -D 777 systemd
sudo apt -f install
Hope it helps.