Could not calculate upgrade to Ubuntu 20 due to failure to remove python-minimal

[Thomas Dowd]

Relase:
Description: Ubuntu 18.04.5 LTS
Release: 18.04

Package version:
 apt-cache policy pkgname ubuntu-release-upgrader
N: Unable to locate package pkgname
N: Unable to locate package ubuntu-release-upgrader

Expected:

After removing all 3rd party -ppas due to the error message:
"
Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade.

 This was likely caused by:
 * Unofficial software packages not provided by Ubuntu
Please use the tool 'ppa-purge' from the ppa-purge
package to remove software from a Launchpad PPA and
try the upgrade again.

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'.
"

Results:
After removing the launchpad ppas the upgrade fails to removing python-minimal

Relevant log snippet:
2020-10-14 18:12:23,395 DEBUG Comparing 4.15.0-118 with
2020-10-14 18:12:23,395 DEBUG Comparing 4.15.0-121 with 4.15.0-118
2020-10-14 18:12:23,567 DEBUG /openCache(), new cache size 66678
2020-10-14 18:12:23,567 DEBUG need_server_mode(): run in 'desktop' mode, (because of pkg 'ubuntu-desktop')
2020-10-14 18:12:23,570 DEBUG quirks: running PreDistUpgradeCache
2020-10-14 18:12:23,570 DEBUG running Quirks.PreDistUpgradeCache
2020-10-14 18:12:23,570 INFO installing python-is-python2 because python-minimal was installed
2020-10-14 18:12:23,570 DEBUG Installing 'python-is-python2' (python-minimal was installed on the system)
2020-10-14 18:12:23,601 INFO removing python-minimal because python-is-python2 is being installed
2020-10-14 18:12:23,601 DEBUG Removing 'python-minimal' (python-is-python2 is being installed on the system)
2020-10-14 18:12:23,601 INFO failed to remove python-minimal
2020-10-14 18:12:25,318 DEBUG Installing 'xserver-xorg-video-all' (Distro KeepInstalledPkgs rule)

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.38
ProcVersionSignature: Ubuntu 4.15.0-121.123-generic 4.15.18
Uname: Linux 4.15.0-121-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.18
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Wed Oct 14 18:17:29 2020
EcryptfsInUse: Yes
InstallationDate: Installed on 2018-03-14 (945 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Release amd64 (20180105.1)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-10-15 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

It seems that you only disabled / removed the PPA's from your apt sources, because the packages from them are still installed the upgrade was not able to be calculated. You'll need to reenable the PPAs and use the tool ppa-purge to remove the packages provided by the PPAs and disable them.

[Launchpad Janitor (janitor)]

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