Bug#1110883: release-notes: mDNS resolution in systemd-resolved disabled by default, breaking existing setups

[Colin Crawford <colin.j.crawford@gmail.com>]

Hi Chris,

Thanks for the quick reply. I'm not a developer, so I'm afraid I don't know what an MR is or how to submit a patch. However, I've taken the text of the relevant NEWS item from the systemd-resolved package as a starting point for the text below. Please let me know if this draft is useful:

For trixie, mDNS support is now globally disabled by default in systemd-resolved.

Users relying on mDNS who are not already using Avahi must mask the
associated drop-in configuration file before upgrading, or the machine may

become unreachable upon package upgrade. To mask the drop-in, do the

following as root:

      mkdir -p /etc/systemd/resolved.conf.d/
      touch /etc/systemd/resolved.conf.d/00-disable-mdns.conf

Best,

Colin

On Tue, Aug 12, 2025 at 3:40 AM Chris Hofstaedtler <zeha@debian.org> wrote:

On Mon, Aug 11, 2025 at 10:20:03PM -0400, Colin J Crawford wrote:
>         With the release of Debian 13 "Trixie," mDNS resolution has been
> disabled in systemd-resolved at a global level, apparently per bug
> 1098914. This can cause mDNS resolution to unexpectedly break in existing
> setups. The changelog for the systemd-resolved package has documentation for
> how to mask the new drop-in configuration file that causes this, but this
> information was not included in the Debian 13 release notes.
>
> As this is a breaking change that can cause local name resolution to fail
> completely for users who are not using Avahi, I believe that this should be
> included in the release notes, most likely in the "Issues to be aware of for
> trixie" section.

I agree, please send an MR / patch / text draft.

Best,
Chris