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Date: Thu, 27 Aug 2026 10:28:45 +0200
From: Sascha Frey <sf@techfak.net>
To: submit@bugs.debian.org
Subject: libvirt-daemon-driver-qemu: libvirt migration fails with QEMU 11:
 unexpected detach parameter
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Package: libvirt-daemon-driver-qemu
Version: 11.3.0-3+deb13u2
Severity: important

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

-- System Information:
Debian Release: 13.6
  APT prefers stable-security
  APT policy: (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 7.1.8+deb13-amd64 (SMP w/24 CPU threads; PREEMPT)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE,
TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8), LANGUAGE
not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libvirt-daemon-driver-qemu depends on:
ii  adduser                     3.152
ii  debconf [debconf-2.0]       1.5.91
ii  libc6                       2.41-12+deb13u3
ii  libgcc-s1                   14.2.0-19
ii  libglib2.0-0t64             2.84.4-3~deb13u3
ii  libgnutls30t64              3.8.9-3+deb13u4
ii  libselinux1                 3.8.1-1
ii  libvirt-common              11.3.0-3+deb13u2
ii  libvirt-daemon-log          11.3.0-3+deb13u2
ii  libvirt0                    11.3.0-3+deb13u2
ii  libxml2                     2.12.7+dfsg+really2.9.14-2.1+deb13u3
ii  logrotate                   3.22.0-1
ii  qemu-system                 1:11.0.2+ds-2~bpo13+1
ii  qemu-system-x86 [qemu-kvm]  1:11.0.2+ds-2~bpo13+1
ii  systemd-container           257.13-1~deb13u1

Versions of packages libvirt-daemon-driver-qemu recommends:
ii  passt        0.0~git20250503.587980c-2+deb13u1
pn  swtpm        <none>
pn  swtpm-tools  <none>

Versions of packages libvirt-daemon-driver-qemu suggests:
pn  numad  <none>

-- Configuration Files:
/etc/logrotate.d/libvirtd.qemu changed [not included]

-- debconf information:
  libvirt-daemon-driver-qemu/id_warning: true
]