cannot upgrade to ubuntu 22.04 LTS from 21.10

[Timm]

Description: Ubuntu 21.10
Release: 21.10

ubuntu-release-upgrader-core:
  Installiert: 1:21.10.9
  Installationskandidat: 1:21.10.9
  Versionstabelle:
 *** 1:21.10.9 500
        500 http://iq.archive.ubuntu.com/ubuntu impish-updates/main amd64 Packages
        500 http://iq.archive.ubuntu.com/ubuntu impish-updates/main i386 Packages
        100 /var/lib/dpkg/status
     1:21.10.8 500
        500 http://iq.archive.ubuntu.com/ubuntu impish/main amd64 Packages
        500 http://iq.archive.ubuntu.com/ubuntu impish/main i386 Packages

I expected to be able to upgrade to 22.04 without issues. However it results in an error message that "it couldn't detect the available system updates, this could be caused by third party PPAs", etc. even though they should be disabled since I recently upgraded from 20.04 to 21.10.

ProblemType: Bug
DistroRelease: Ubuntu 21.10
Package: ubuntu-release-upgrader-core 1:21.10.9
ProcVersionSignature: Ubuntu 5.13.0-52.59-generic 5.13.19
Uname: Linux 5.13.0-52-generic x86_64
ApportVersion: 2.20.11-0ubuntu71.2
Architecture: amd64
CasperMD5CheckResult: unknown
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Mon Jul 4 17:44:09 2022
InstallationDate: Installed on 2020-07-16 (718 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to impish on 2022-07-04 (0 days ago)
VarLogDistupgradeTermlog:

mtime.conffile..etc.update-manager.release-upgrades: 2022-07-04T17:39:53.700157