Upgrade to 20.04 fails "Could not calculate the upgrade"

[Sean Hendricks]

Looking at the apt.log would seem to indicate that the upgrade fails somewhere when investigating python.

I have removed all PPAs as far as I can tell, so that shouldn't be the issue.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.40
ProcVersionSignature: Ubuntu 4.15.0-124.127-generic 4.15.18
Uname: Linux 4.15.0-124-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.20
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Fri Nov 27 18:37:19 2020
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 2020-11-27 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1889250, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.