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Upgrade a Hypervisor from Debian 12 to Debian 13

VirtFusion supports Debian 13 (Trixie) hypervisors from v7.0.0. An existing Debian 12 (Bookworm) hypervisor can be upgraded in place rather than reinstalled. The upgrade is Debian's own release upgrade plus one VirtFusion step: the VirtFusion package repository has a suite per Debian release, so it has to be switched to trixie along with Debian's own sources, and its packages are then upgraded with everything else.

The upgrade ends with a reboot, which stops every server on the hypervisor until it comes back, so it needs a maintenance window.

Before you start
  • The control server must be on v7.0.0 or later.
  • Have console access to the hypervisor (IPMI, iDRac or similar). A hypervisor that does not come back from the reboot cannot be repaired over SSH.
  • Check df -h / and /boot: the upgrade downloads and unpacks a full set of packages.

1. Prepare the hypervisor in VirtFusion​

  1. Open the hypervisor in the administration area and enable Maintenance under its settings, so no new servers are placed on it while you work.
  2. Leave the servers running. They stop with the reboot and start again by themselves when the hypervisor comes back. Do not shut them down from VirtFusion for the upgrade: a server stopped from VirtFusion is recorded as stopped and is not started at boot.

2. Bring Debian 12 fully up to date​

On the hypervisor, over SSH as root:

apt update
apt full-upgrade
apt autoremove

If a new kernel was installed, reboot before going on, so the release upgrade starts from a clean system.

3. Switch the package sources to Trixie​

Change every reference to bookworm to trixie, in Debian's sources and in VirtFusion's:

sed -i 's/bookworm/trixie/g' /etc/apt/sources.list
sed -i 's/bookworm/trixie/g' /etc/apt/sources.list.d/*.list
grep -r bookworm /etc/apt/sources.list /etc/apt/sources.list.d/

The last command must print nothing. The VirtFusion repository line in /etc/apt/sources.list.d/virtfusion.list should now read:

deb http://packages.virtfusion.net/debian trixie main

If the hypervisor used bookworm-backports, remove that line rather than renaming it: Trixie's own packages are newer than Bookworm's backports. Any other third-party repository (a backup client, a monitoring agent) needs a Trixie suite of its own; check its vendor before continuing.

4. Upgrade​

apt update
apt upgrade --without-new-pkgs
apt full-upgrade

The second command upgrades what it can without installing new packages, the third does the rest, including the new kernel, libvirt and QEMU. Read what apt full-upgrade proposes to remove before confirming: nothing from the VirtFusion repository, and neither libvirt nor QEMU, should be on that list.

When asked about a configuration file you have changed, keep the current version. What VirtFusion installed and configured itself is not touched by the upgrade.

Running servers keep running through the package upgrade. Libvirt restarts and reconnects to them; QEMU's new version is used by servers from their next start.

5. Reboot​

apt autoremove
reboot

The hypervisor comes back on the Trixie kernel and the servers that were running start again.

6. Check the result​

cat /etc/debian_version
systemctl is-active libvirtd
virsh list

Expect a 13.x version, libvirt active, and the servers that were running listed as running.

If the hypervisor does not come online in VirtFusion afterwards, the repository switch in step 3 is the first thing to check: /etc/apt/sources.list.d/virtfusion.list must name trixie. Correct it, then run apt update and apt full-upgrade again.

Then in VirtFusion, check that the hypervisor shows as online and its servers as running, and disable Maintenance.

Notes​

  • Debian 13's ebtables and iptables commands are the nftables-backed ones. The native network filters work on them without change; nothing has to be installed or switched.
  • Debian 13 can convert /etc/apt/sources.list to the newer deb822 format with apt modernize-sources. This is optional and makes no difference to VirtFusion.
  • A fresh Debian 13 installation remains the cleaner path for a hypervisor with nothing on it; the installation guide covers it.
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