Can't upgrade to Ubuntu 20.04 due to python issues

[Michał Margula]

Can't upgrade to Ubuntu 20.04, even with -p switch. Getting plenty of following messages in apt.log

Broken python-is-python2:amd64 Depends on python2:amd64 < none | 2.7.17-2ubuntu4 @un umH >
  Considering python2:amd64 1 as a solution to python-is-python2:amd64 -1
  Ignore MarkKeep of python-is-python2:amd64 < none -> 2.7.17-4 @un pumN Ib > as its mode (Install) is protected
  Removing python-is-python2:amd64 rather than change python2:amd64
  Ignore MarkDelete of python-is-python2:amd64 < none -> 2.7.17-4 @un pumN Ib > as its mode (Install) is protected

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.42
ProcVersionSignature: Ubuntu 4.15.0-141.145-generic 4.15.18
Uname: Linux 4.15.0-141-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.23
Architecture: amd64
CrashDB: ubuntu
Date: Tue Apr 13 21:12:59 2021
InstallationDate: Installed on 2018-03-28 (1111 days ago)
InstallationMedia: Ubuntu-Server 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US:en
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2021-04-13 (0 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Brian Murray (brian-murray)]

Thanks for taking the time to report this upgrade failure. There is currently a new version of the release upgrader available in -proposed which may resolve the error you've encountered. Please run the following command to test the new version of the upgrader:

  do-release-upgrade -p

Please lets us know the results in this bug report. Thanks again and good luck!

[Michał Margula (michal-z)]

Hi Brian,

Apologies for late reply, I just tried `do-release-upgrade -p` but it did not help. Please find apt.log attached. I will also attach main.log and apt-clone_system_state.tar.gz in following notes.

Kind regards,
Michał

[Launchpad Janitor (janitor)]

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