Dear Maintainer,

After upgrading our VM hosts from Debian 12 to Debian 13 (trixie),
live migration of VMs from the upgraded hosts started failing.

The affected hosts use:

  libvirt 11.3.0-3+deb13u2
  qemu-system-x86 1:11.0.2+ds-2~bpo13+1

The QEMU processes were restarted after the Debian upgrade, so all
running VMs were using the new QEMU version.

I attempted a normal live migration using virsh, for example:

  virsh -c qemu+ssh://SOURCE/system migrate \
      --live --persistent --undefinesource \
      VMNAME \
      qemu+ssh://DEST/system \
      tcp://migrate.DEST/

The migration fails with:

  error: internal error: unable to execute QEMU command 'migrate':
  Parameter 'detach' is unexpected

The problem can also be reproduced directly through QMP:

  virsh qemu-monitor-command VMNAME --pretty \
    '{"execute":"migrate","arguments":{"detach":true}}'

QEMU 11 responds with:

  Parameter 'detach' is unexpected

I locally backported the upstream libvirt change
"qemuMonitorJSONMigrate: Drop 'detach' QMP option" to
11.3.0-3+deb13u2.

After rebuilding and installing the modified libvirt package,
live migration works successfully again.

I therefore believe the Debian trixie libvirt package needs the
upstream fix for compatibility with QEMU 11.

Please consider backporting this upstream fix to the trixie package.
Alternatively, a newer libvirt version could be made available
through trixie-backports.

Upstream patch:
https://www.mail-archive.com/devel@lists.libvirt.org/msg10575.html