Upgrading ubuntu 18.10 to latest in incremental steps...

[Tom H]

On Mon, Jul 6, 2020 at 4:35 PM Gilles Gravier <ggravier at fsfe.org> wrote:
>
> I have an old machine running 18.10. When I do sudo
> do-release-upgrade it complains that it can't upgrade from cosmic to
> eoan.
>
> How can I force update first to 19.04 (disco), then 19.10. then
> 20.04?

19.04 has been EOLd, so you'll have to change your "sources.list" to
upgrade to 19.04 to

deb http://old-releases.ubuntu.com/ubuntu disco main ...
deb http://old-releases.ubuntu.com/ubuntu disco-updates main ...
deb http://old-releases.ubuntu.com/ubuntu disco-security main ...

Theoretically, you could then run "apt update ; apt full-upgrade", but
I'd be more careful if I were you and run

apt update
apt install linux-image-generic systemd dpkg apt util-linux
apt upgrade
apt full-upgrade

You can even use more discrete steps, but given that there are six
months between releases, this should be enough.

You'll have to do the same to upgrade from 19.04 to 19.10.

You'll then be able to use "do-release-upgrade" to upgrade from 19.10 to 20.04.