Comment 2 for bug 1998086

Reviewing the files from your upgrade attempt, you have installed packages from the deadsnakes PPA. Some of the packages installed are newer than those in the official archive, which is keeping some python packages installed which then prevents the upgrade from being calculated. Please try using the ppa-purge tool to remove packages installed from ppa:deadsnakes/ppa. After that you can try upgrading again and if it still fails open a new bug report. Thanks and good luck!