Upgrade from 18.04 to 20.04 not working

[Christine]

When attempting to upgrade to ubuntu 20.04 through Software Updater, I receive this message:

Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade.

 If none of this applies, then please report this bug using the command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal. If you want to investigate this yourself the log files in '/var/log/dist-upgrade' will contain details about the upgrade. Specifically, look at 'main.log' and 'apt.log'.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.38
ProcVersionSignature: Ubuntu 4.15.0-118.119-generic 4.15.18
Uname: Linux 4.15.0-118-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.17
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Thu Sep 24 18:35:11 2020
InstallationDate: Installed on 2019-02-08 (593 days ago)
InstallationMedia: Ubuntu 16.04.4 LTS "Xenial Xerus" - Release amd64 (20180228)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-09-24 (0 days ago)
VarLogDistupgradeTermlog:

mtime.conffile..etc.update-manager.release-upgrades: 2020-09-24T17:52:46.274401

[Daniel Letzeisen (dtl131)]

Is it possible for you to remove nodejs and reinstall it after the update?

Broken nodejs:amd64 Depends on python-minimal:amd64 < 2.7.15~rc1-1 @ii gR >

[Christine (c-d-riley)]

Thank you for the suggestion Daniel. I used Synaptic Package Manager to search for nodejs. Four entries were found (nodejs, -dev, -doc and -mozilla) but when I right-clicked on each entry, it said "mark for installation". Also, there is nothing listed under "installed version". So I assume there aren't any nodejs packages installed. Or is there another way to find them, I'm not aware of? Like through terminal commands.

[Daniel Letzeisen (dtl131)]

I don't even seen the nodejs line I quoted in the log now. I may have been looking at another bug and got my tabs mixed up. My apologies.

[Christine (c-d-riley)]

Thanks for the clarification, Daniel.

[Christine (c-d-riley)]

I ran "grep Broken /var/log/dist-upgrade/apt.log" in terminal, after yet another failed attempt to upgrade, and got this:

Broken python-dev:amd64 Depends on python:amd64 < 2.7.15~rc1-1 @ii gR > (= 2.7.15~rc1-1)
Broken python2:amd64 Breaks on python:amd64 < 2.7.15~rc1-1 @ii gK Ib > (< 2.7.15-2)
Broken python-all-dev:amd64 Depends on libpython-all-dev:amd64 < 2.7.15~rc1-1 | 2.7.17-2ubuntu4 @ii umH > (= 2.7.17-2ubuntu4)
Broken python2-dev:amd64 Breaks on python-dev:amd64 < 2.7.15~rc1-1 @ii mK Ib > (< 2.7.15-2)
Broken libpython2-dev:amd64 Breaks on libpython-dev:amd64 < 2.7.15~rc1-1 @ii mK > (< 2.7.15-2)
Broken python-dev:amd64 Depends on python:amd64 < 2.7.15~rc1-1 @ii gR > (= 2.7.15~rc1-1)
Broken python2:amd64 Breaks on python:amd64 < 2.7.15~rc1-1 @ii gK Ib > (< 2.7.15-2)
Broken python-all-dev:amd64 Depends on python2-dev:amd64 < none | 2.7.17-2ubuntu4 @un uH > (= 2.7.17-2ubuntu4)
Broken libpython-all-dev:amd64 Depends on libpython2-dev:amd64 < none | 2.7.17-2ubuntu4 @un uH > (= 2.7.17-2ubuntu4)
Broken python-dev:amd64 Depends on python:amd64 < 2.7.15~rc1-1 @ii gR > (= 2.7.15~rc1-1)
Broken python2:amd64 Breaks on python:amd64 < 2.7.15~rc1-1 @ii gK Ib > (< 2.7.15-2)
Broken python-all:amd64 Depends on python2:amd64 < none | 2.7.17-2ubuntu4 @un umH > (= 2.7.17-2ubuntu4)
Broken python:amd64 PreDepends on python-minimal:amd64 < 2.7.15~rc1-1 @ii gR > (= 2.7.15~rc1-1)
Broken python:amd64 Depends on libpython-stdlib:amd64 < 2.7.15~rc1-1 @ii gR > (= 2.7.15~rc1-1)
Broken python-is-python2:amd64 Depends on python2:amd64 < none | 2.7.17-2ubuntu4 @un umH >
Broken python-is-python2:amd64 Breaks on python:amd64 < 2.7.15~rc1-1 @ii gK >
Broken python-dev:amd64 Depends on python:amd64 < 2.7.15~rc1-1 @ii gR > (= 2.7.15~rc1-1)
Broken libpython2-stdlib:amd64 Breaks on libpython-stdlib:amd64 < 2.7.15~rc1-1 @ii gK > (< 2.7.15-2)
Broken python2-minimal:amd64 Breaks on python-minimal:amd64 < 2.7.15~rc1-1 @ii gK > (< 2.7.15-2)
Broken python2:amd64 PreDepends on python2-minimal:amd64 < none | 2.7.17-2ubuntu4 @un umH > (= 2.7.17-2ubuntu4)
Broken python-all:amd64 Depends on python2:amd64 < none | 2.7.17-2ubuntu4 @un umH > (= 2.7.17-2ubuntu4)
Broken python-is-python2:amd64 Depends on python2:amd64 < none | 2.7.17-2ubuntu4 @un umH >

Something seems to be up with python. Can anyone help me find a solution?

[Nineesh K (nineesh)]

I think uninstalling already installed python2 packages using:

sudo apt purge libpython2*

Once uninstall completed you can reinstall python2 with:

sudo apt install python

Seems it will fix the issue..

[Launchpad Janitor (janitor)]

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