unresolvable problem upgrading 18.04 to 20.04

[Stripes Theotoky]

I took the following steps with this result.

lsb_release -rd
Description: Ubuntu 18.04.6 LTS
Release: 18.04

sudo apt update
sudo apt upgrade
sudo apt autoremove

find /etc/apt/sources.list.d -type f -name "*.list" -print0 | while read -d $'\0' file; do awk -F/ '/deb / && /ppa\.launchpad\.net/ {print "sudo ppa-purge ppa:"$4"/"$5}' "$file"; done

sudo ppa-purge ppa:otto-kesselgulasch/gimp
sudo ppa-purge ppa:atareao/telegram
sudo ppa-purge ppa:obsproject/obs-studio

sudo do-release-upgrade

Calculating the changes

Could not determine the upgrade

An unresolvable problem occurred while calculating the upgrade.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.45
ProcVersionSignature: Ubuntu 4.15.0-213.224-generic 4.15.18
Uname: Linux 4.15.0-213-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.29
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Sat Jan 20 11:29:58 2024
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-xenial-amd64-20160624-2
InstallationDate: Installed on 2017-07-14 (2380 days ago)
InstallationMedia: Ubuntu 16.04 "Xenial" - Build amd64 LIVE Binary 20160624-10:47
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2024-01-20 (0 days ago)
mtime.conffile..etc.update-manager.release-upgrades: 2018-08-01T09:28:36.284395