Dear Maintainer,

*** Reporter, please consider answering these questions, where appropriate ***

   * What led up to the situation?
        Starting any virtual pc with virtManager
   * What exactly did you do (or not do) that was effective (or
     ineffective)?
   * What was the outcome of this action?
Error report VirtManager:
        Fehler beim Starten der Domain: Operation not supported: operation
'setCpusetMemoryMigrate' not supported

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 75, in
cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 111, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 66,
in newfn
    ret = fn(self, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/object/domain.py", line 1279, in
startup
    self._backend.create()
  File "/usr/lib/python3/dist-packages/libvirt.py", line 1080, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirt.libvirtError: Operation not supported: operation
'setCpusetMemoryMigrate' not supported

   * What outcome did you expect instead?
        Just starting the VM like day before.

*** End of the template - remove these template lines ***

Same issue. Buster-backports enabled.

libvirtd makes the virtual machines boot again.

I can confirm this on a Debian Buster with backports enabled, workaround
mentioned is working.

A similar issue was pushed to redhat tracker, and it seems that
libvirt5.1 might fix the issue:
https://bugzilla.redhat.com/show_bug.cgi?id=1688736