do-release-upgrade fails when upgrading to 22.04 "An unresolvable problem occurred"

[Luca Hermes]

I'm trying to upgrade my system from Ubuntu version 20.04 to 22.04 via `do-release-upgrade`. The command fails with "An unresolvable problem occurred while calculating the upgrade."

I did some research and found that external software sources may be the issue, but I can't figure out which ones are causing the issue for me. Any help is greatly appreciated.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubuntu-release-upgrader-core 1:20.04.40
ProcVersionSignature: Ubuntu 5.4.0-144.161-generic 5.4.229
Uname: Linux 5.4.0-144-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.25
Architecture: amd64
CasperMD5CheckResult: skip
CrashDB: ubuntu
CurrentDesktop: Unity:Unity7:ubuntu
Date: Thu Mar 9 16:37:02 2023
InstallationDate: Installed on 2017-06-11 (2096 days ago)
InstallationMedia: Ubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.2)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to focal on 2023-03-09 (0 days ago)

[Luca Hermes (lucahermes)]

I found several hints that this should be posted as a question - I am unsure that this is a bug