How upgrade Ubuntu 20.10 after its EOL?

Solution 1:

By some reason http://old-releases.ubuntu.com/ubuntu/dists/ does not list groovy (20.10), while really it is EOL since July 22, 2021.

So you have to change old-releases back to archive in the sources.list:

sudo sed -i "s/old-releases/archive/g" /etc/apt/sources.list /etc/apt/sources.list.d/*.list
sudo apt-get update
sudo apt-get dist-upgrade

Running EOL version is dangerous and non-productive, so it is recommended to upgrade 20.10 (EOL) to 21.04 (actual, hirsute) by rebooting machine and running standard procedure like

sudo do-release-upgrade

or

update-manager -c

Solution 2:

This can be done without reinstalling or modding your sources.list. I was able to upgrade from 20.10 -> 21.04 -> 21.10.

If running sudo do-release-upgrade fails like so

Please install all available updates for your release before upgrading.

then you will need to remove apt's cache (broken links) before sudo apt upgrade will succeed.

sudo rm -rf /var/lib/apt/lists/*
sudo apt update
sudo apt upgrade

Nevertheless the sudo do-release-upgrade command will still fail since it doesn't have a direct path to 21.10 anymore

An upgrade from 'groovy' to 'impish' is not supported with this tool.

so you can use this workaround and upgrade to 21.04 first.

wget http://archive.ubuntu.com/ubuntu/dists/hirsute-updates/main/dist-upgrader-all/current/hirsute.tar.gz
mkdir upgrader
tar -xaf hirsute.tar.gz -C upgrader
cd upgrader
sudo ./hirsute

Reboot into 21.04 and apt update should be working like normal but you might as well upgrade to 21.10 to stay ahead of this problem.

sudo apt update && sudo apt upgrade
sudo do-release-upgrade

This is a good reason to stick with LTS once 22.04 is released in April.

Solution 3:

Tried to apt update and upgrade EOL Groovy based unit.
Hints from N0rbert are good, however groovy is neither in http://old-releases.ubuntu.com/ubuntu/dists/ nor in http://archive.ubuntu.com/ubuntu/dists/. Tried also us.archive and local <countrycode>.archive .. groovy is gone.

Therefore apt update fails with errors as in original post.
And do-release-upgrade just keeps telling me to run do-release-upgrade as "Your Ubuntu release is not supported anymore."
Unexpected "Vicious circle" in update loop and 'issue' on mature OS like Ubuntu.

sudo sed -i "s/groovy/focal/g" /etc/apt/sources.list /etc/apt/sources.list.d/*.list /etc/apt/sources.list.d/*.sources
sudo apt-get dist-upgrade

Above commands got me back to 20.04 Focal Fossa. Supported OS.
Now waiting for 22.04.?? Jammy Jellyfish based LTS.