Edit: After some time, Ubuntu's archive.ubuntu.com
repositories are moved to old-releases.ubuntu.com
. This is what happened for the tar I linked. I updated the link. Moreover, it seems that the bug will be (or already is) resolved: see Ubuntu Bug #1975533
I had similar problem. The only way of upgrading that worked in my case was:
wget http://old-releases.ubuntu.com/ubuntu/dists/hirsute-updates/main/dist-upgrader-all/current/hirsute.tar.gz
tar -xvf hirsute.tar.gz
sudo ./hirsute
Details here: https://blog.invid.eu/2022/02/24/upgrade-eol-ubuntu-server-from-20-10-to-21-10-an-upgrade-from-groovy-to-impish-is-not-supported-with-this-tool-ubuntu-ubuntugeek-ubuntu-linux-eol-upgrade/
I wanted to upgrade from 20.10 to 22.04, but the intermediate step was to upgrade from 20.10 to 21.04. Nevertheless, the procedure should work for any past and future Ubuntu distribution.
Note! Before running the UpgradeTool
I added the old-releases.
to the domains/entries in the /etc/apt/sources.list
. Operation similar to the one described in randomcontrol's answer:
sudo sed -i -e 's/archive.ubuntu.com\|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list
so that the:
sudo apt-get update
would work.
Additional information on that approach in the official documentation: https://help.ubuntu.com/community/EOLUpgrades