Need to Upgrade Mate 19.10 to 20.04 LTS but support has expired

[radix55]

Hello,
I have a mission critical server running on Mate 19.10.
Unfortunately, I forgot to check the support expiration date for that version and now I'm no more able to access Mate's automatic software upgrade features because every time I run the "update-manager" command I always receive the message:
<The repository "http://archive.ubuntu.com/ubuntu eoan Release" does not have a Release file>

Is there an alternative repository to configure on mate to bypass such an annoying problem?

Alternatively, how can I perform the update to 20.04 LTS without re-installing all the software and data present on my server ?

Is it possibile to perform the upgrade offline (by using the .iso install file downloaded from the ubuntu mate site) without losing all the data, information and applications installed on my server ?

Thanks in advance for your support,
Cristiano

[HJV]

Not sure any of that is possible on an interim release which is used somewhat as test bed for new features before Long Term Support release comes out. Unless someone knows better, I would try to switch to the previous 20.04 LTS which on Mate is supported for 3 years and then switch to the 22.04 LTS in April 2022. The LTS is better suited for a critical system unlike the interim releases which are only supported for 9 months. Alternatively, perhaps you can upgrade to the 21.10 interim release that came out last month and then next year when the LTS comes you can smoothly transition to that? Hope this helps or someone else chimes-in with a better response. Best regards.

[tkn]

I have a mission critical server running on Mate 19.10.

oops...
well, before we start I really would like to try convince you of the following things:

1. never run a mission critical server on an interim release, always choose LTS
2. really try to get out of the habit of running a desktop OS for a mission critical server
3. really try to avoid the use of a GUI on a mission critical server.
4. Best to use the Ubuntu-server distro if your server is mission critical and needs uninterrupted uptime (Ubuntu-server is commandline only)

With that out of the way, let's continue.

Alternatively, how can I perform the update to 20.04 LTS without re-installing all the software and data present on my server ?

I assume you followed best practice and have a full and recent backup ?
(not that you will need it...just as safety precaution when things go sideways)

sudo do-release-upgrade

I can not guarantee that all of your software will survive this upgrade but usually it will without a hitch.

If you just use the more mainstream packages, nothing problematic will happen.

But if you use more exotic or obscure software packets then you might encounter that one or two of them have been replaced or do not exist at all anymore so be sure to check the repositories of 20.04 if the software you use is still available.

If you are missing some application, try to find out if it has a PPA or if it is available for a current version of Debian. In the worst case scenario you could always manually download the packet from an older distro or compile it yourself from source.

Besides this compulsory disclaimer: Yes it will upgrade everything automagically.

good luck

EDIT: Take note of @Norbert_X 's advice below, especially if you missed some updates

[Norbert_X]

Welcome to Ubuntu MATE community, @radix55!

You have to carefully replace all occurencies of

http://archive.ubuntu.com/ubuntu eoan

to

http://old-releases.ubuntu.com/ubuntu eoan

in /etc/apt/sources.list and /etc/apt/sources.list.d/*.list and then run
sudo apt-get update followed by sudo apt-get dist-upgrade to get latest upgrades for 19.10.

Then reboot and run an upgrade to 20.04 LTS as usual using sudo do-release-upgrade

[Spyder]

I think you can upgrade with Software updater, provided it is set to notify you of all available releases.

Using an even older Ubuntu 1904 as a test case, after the "Failed to Download Repository Information" notice, I click on OK and get this second notice offering to upgrade to 20.04.3.

Click on "Upgrade" and it starts the process.

Note. This was done on 11 Nov 2021. I assume Ubuntu MATE would respond the same, but to Ubuntu MATE 20.04.

UPDATE: Sorry to report this is does not work with 19.04. Above, I went through two screens initially and stopped. Checking again later and going further, I run into this message:

You would have to try and see if it completes with 19.10 as the starting point. I have nothing to test that with.

The good news is that with later releases, like 20.10, you CAN upgrade even after the 20.10 refuses to do software updates. I did this about two weeks ago, upgrading 20.10 to 21.04.

Furthermore, when 21.04 is end of life sometime in January, you should be able to go directly to 21.10 from 20.10, skipping over 21.04 - experts on the Ubuntu Forum say this will be possible.