N: Missing Signed-By in the sources.list(5) entry for ''

I have looked into upgrading from Ubuntu 22 LTS to 24 LTS and found out there is no direct path without going through 23 first. I was able to successfully upgrade my way to 24.04 and my server software is running fine.

Unfortunately running apt update as root yields these messages:

N: Missing Signed-By in the sources.list(5) entry for ''
N: Missing Signed-By in the sources.list(5) entry for ''
N: Missing Signed-By in the sources.list(5) entry for ''

I’m not sure they are warnings, and not even AI is able to help me fix this. The only solution I found was related to a New Zealand mirror, not Digital Ocean1.

How can I fix this? How should I have googled this better?

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Bobby Iliev
Site Moderator
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June 13, 2024
Accepted Answer


Can you share the contents of your /etc/apt/sources.list.d/ubuntu.sources file?

cat /etc/apt/sources.list.d/ubuntu.sources

I just created a new Ubuntu 24.04 server and the DigitalOcean mirror definition in that file is as follows:

## See the sources.list(5) manual page for further settings.
Types: deb
Suites: noble noble-updates noble-backports
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

## Ubuntu security updates. Aside from URIs and Suites,
## this should mirror your choices in the previous section.
Types: deb
Suites: noble-security
Components: main universe restricted multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

Does this match your configuration as well?

On a side note, pne thing to keep in mind is that whenever doing such large OS upgrades it is best to have a snapshot of your Droplet. That way in case of anything going wrong, you can restore back to a working version of your server.

Ideally, I think the safest path that maximizes speed is to make a snapshot, make a duplicate Droplet from it, do the upgrade on the duplicated Droplet. If it works, then you can decide how important that IP and uptime is to you and either stick with the new one or upgrade the old one.

If the upgrade does not work well, you know to set aside some time and then do a migration as discussed here:

- Bobby

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