Comment 3 for bug 1954854

Thanks for the info Michael,
without steps to reproduce I see two paths from here.

## #1 trying different versions

As Paride asked it might be worth to check different versions.
There is no super-convenient way to downgrade bind9

You can add all of Bionics (or any other release in between cosmic, disco, eoan) to apt like:
root@f:~# cp /etc/apt/sources.list /etc/apt/sources.list.d/bionic.list
root@f:~# vim /etc/apt/sources.list.d/bionic.list
# herein replace all "focal" with bionic
root@f:~# apt update
root@f:~# apt-cache policy bind9
bind9:
  Installed: (none)
  Candidate: 1:9.16.1-0ubuntu2.9
  Version table:
     1:9.16.1-0ubuntu2.9 500
        500 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages
     1:9.16.1-0ubuntu2 500
        500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
     1:9.11.3+dfsg-1ubuntu1.16 500
        500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     1:9.11.3+dfsg-1ubuntu1 500
        500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages
# A downgrade to bionics 9.11.3 would then be:
root@f:~# v=1:9.11.3+dfsg-1ubuntu1.16; apt install bind9=$v bind9utils=$v

# Warning, this might mess up your dependencies and installed packages, I'd recommend doing this on a test system or with a full backup to restore after testing.

## #2 Full debugging

As you report that your offsets seem to be reliable aou could try to attach a full crash of bind9 if it generates one.

So if there is /var/crash/...bind9...crash
then try running
  $ sudo apport-collect 1954854

That should attach all logs and version information.

Then (if not auto-attached) add the crash file as well.
We could then try to get a full gdb backtrace, maybe that indicates an obvious issue or an error known by upstream.