ubuntu-release-upgrader Could not calculate the upgrade An unresolvable problem occurred while calculating the upgrade. after purging all 3rd party repositories and software

All non-snap packages have been pureged and their sources have deleted from the sources lists. I cannot find any hints in /var/log/dist-upgrade/main.log.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: ubuntu-release-upgrader-core 1:22.04.15
ProcVersionSignature: Ubuntu 5.15.0-56.62-lowlatency 5.15.64
Uname: Linux 5.15.0-56-lowlatency x86_64
ApportVersion: 2.20.11-0ubuntu82.2
Architecture: amd64
CasperMD5CheckResult: unknown
CrashDB: ubuntu
CrashReports:
 644:1000:114:0:2022-12-10 11:32:31.841995148 +0100:2022-12-10 11:32:31.841995148 +0100:/var/crash/_usr_lib_x86_64-linux-gnu_libexec_drkonqi.1000.upload
 640:1000:114:1013221:2022-12-10 11:32:31.841995148 +0100:2022-12-10 11:32:31.925207223 +0100:/var/crash/_usr_lib_x86_64-linux-gnu_libexec_drkonqi.1000.crash
 600:108:114:37:2022-12-10 11:32:34.918153353 +0100:2022-12-10 11:32:34.918153353 +0100:/var/crash/_usr_lib_x86_64-linux-gnu_libexec_drkonqi.1000.uploaded
CurrentDesktop: ubuntu:GNOME
Date: Sat Dec 17 17:00:25 2022
InstallationDate: Installed on 2016-09-26 (2272 days ago)
InstallationMedia: Ubuntu-GNOME 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160720)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to jammy on 2022-12-17 (0 days ago)
mtime.conffile..etc.update-manager.release-upgrades: 2022-07-23T23:29:49.039745