"No valid sources.list entry found" and "An upgrade might not succeed" when running "sudo do-dist-upgrade -d" on Ubuntu 23.10

[Paul Smith]

I receive the message following message when performing a "sudo do-release-upgrade -d" on both my Ubuntu 23.10 system(s):

Fetched 23.8 kB in 0s (0 B/s)
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Fetched 0 B in 0s (0 B/s)

Updating repository information

No valid sources.list entry found

While scanning your repository information no entry about mantic
could be found.

An upgrade might not succeed.

Do you want to continue anyway?

Continue [yN]

The message "An upgrade might not succeed" is of concern, so obviously I can't proceed with the upgrade.

My sources.list.d directory looks like this:

cvpsmith@tars:/etc/apt/sources.list.d$ ls
cubic-wizard-ubuntu-release-mantic.sources slack.list
google-chrome.sources spotify.sources
jonaski-ubuntu-strawberry-lunar.sources teams.list
mozillateam-ubuntu-ppa-mantic.sources ubuntu.sources
nvhpc.list

And here are the contents of "ubuntu.sources":

Types: deb
URIs: http://archive.ubuntu.com/ubuntu
Suites: mantic mantic-updates mantic-security mantic-backports
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

As is evident, removing "vscode.list" from sources.list.d/ has no effect.

lsb_release -rd
No LSB modules are available.
Description: Ubuntu 23.10
Release: 23.10

[Nick Rosbrook (enr0n)]

Can you please attach the actual files so we can see the contents of the sources?

[Paul Smith (cvpsmith)]

No problem. Let me know if you need anything else.

[Nick Rosbrook (enr0n)]

Thanks. I was able to re-produce this using your sources. The problem is that you have a mix of .sources and .list PPAs enabled, and since there are at least _some_ .list still present, the upgrader expects Ubuntu sources to be present in a .list file (even though they are already found in /etc/apt/sources.list.d/ubuntu.sources).

So, this is clearly a bug in ubuntu-release-upgrader. But, as a workaround, you should be able to either (a) temporarily remove your /etc/apt/sources.list.d/*.list files, or (b) convert them to .sources. The upgrade should work after that.

[Paul Smith (cvpsmith)]

This fixed the problem. Thanks! Although, I wonder if this will affect others who try to upgrade to 24.04 when it releases tomorrow? That's part of the reason that I went ahead and posted the bug rather than just waiting for the release date.