An unresolvable problem occurred while calculating the upgrade. 18.04 to 20.04

[Tugurlan]

I have removed all ppas as well as removing some packages via

apt remove $(apt-forktracer | grep -i ppa | awk '{print $1}')

The error does not indicate where the problem might be.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.38
Uname: Linux 5.7.1-050701-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.17
Architecture: amd64
CrashDB: ubuntu
Date: Sun Sep 20 15:22:19 2020
InstallationDate: Installed on 2018-08-26 (756 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-09-20 (0 days ago)
mtime.conffile..etc.update-manager.release-upgrades: 2020-08-22T23:06:48.773333

[Jouni Mettala (jouni-mettala)]

VarLogDistupgradeAptlog.txt shows you have some packages from oibaf ppa installed.

[Tugurlan (tugurlann)]

Running ppa purge retruns this:

ppa-purge ppa:oibaf/graphics-drivers
Updating packages lists
PPA to be removed: oibaf graphics-drivers
Warning: Could not find package list for PPA: oibaf graphics-drivers

[Daniel Letzeisen (dtl131)]

I think the issue may be that you removed the oibaf (and other) PPA(s) from your package list before using ppa-purge. Try re-adding it and then running ppa-purge.
ppa-purge will remove the PPA from your sources after reverting packages, so you do not have to do that manually.

sudo add-apt-repository ppa:oibaf/graphics-drivers
sudo ppa-purge ppa:oibaf/graphics-drivers

[Launchpad Janitor (janitor)]

[Expired for ubuntu-release-upgrader (Ubuntu) because there has been no activity for 60 days.]