Graphical Upgrade from 18.04 to 20.04 refused to continue due to an unresolvable bug

[Michele Mattioni]

This is the text that the Graphical Upgrades gave to me

"""
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 1:18.04.44
ProcVersionSignature: Ubuntu 4.15.0-154.161-generic 4.15.18
Uname: Linux 4.15.0-154-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.24
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Wed Aug 18 12:22:27 2021
EcryptfsInUse: Yes
InstallationDate: Installed on 2018-02-27 (1267 days ago)
InstallationMedia: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2021-08-18 (0 days ago)
VarLogDistupgradeTermlog: