Comment 6 for bug 338283

Correction: The error is slightly different in virt-manager 0.7.0:

raceback (most recent call last):
  File "/usr/local/share/virt-manager/virtManager/engine.py", line 272, in show_details
    details = vmmDetails(self.get_config(), con.get_vm(uuid), self)
  File "/usr/local/share/virt-manager/virtManager/details.py", line 337, in __init__
    self.update_widget_states(self.vm, self.vm.status())
  File "/usr/local/share/virt-manager/virtManager/details.py", line 837, in update_widget_states
    self.try_login()
  File "/usr/local/share/virt-manager/virtManager/details.py", line 1266, in try_login
    protocol, host, port, trans, username = self.vm.get_graphics_console()
  File "/usr/local/share/virt-manager/virtManager/domain.py", line 638, in get_graphics_console
    self.update_xml()
  File "/usr/local/share/virt-manager/virtManager/domain.py", line 89, in update_xml
    self._xml = self.vm.XMLDesc(libvirt.VIR_DOMAIN_XML_SECURE)
  File "/usr/lib/python2.6/dist-packages/libvirt.py", line 231, in XMLDesc
    if ret is None: raise libvirtError ('virDomainGetXMLDesc() failed', dom=self)
libvirtError: Unknown failure

This is paired with libvirt in Jaunty, version 0.6.1-0ubuntu5

Using my VNC viewer to the Domain-0 machine works fine.