I am upgrading from 18.04 to 22.04. Upgrade to 20.04 went fine, 22.04 fails

[Pete Cameron]

I needed to upgrade an old system from 18.04 to 22.04, I used standard software updater app.

First upgrade to 20.04 went very smoothly.

Second upgrade has failed repeatedly with the message:

Could not determine 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'.

After this the upgrade is rolled back.

======================
lsb_release -rd
Description: Ubuntu 20.04.5 LTS
Release: 20.04
======================

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubuntu-release-upgrader-core 1:20.04.40
ProcVersionSignature: Ubuntu 5.4.0-144.161-generic 5.4.229
Uname: Linux 5.4.0-144-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.25
Architecture: amd64
CasperMD5CheckResult: skip
CrashDB: ubuntu
Date: Wed Mar 8 17:33:09 2023
InstallationDate: Installed on 2017-02-14 (2213 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_GB:en
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to focal on 2023-03-08 (0 days ago)
VarLogDistupgradeTermlog: