Hello, Since updating to libvirt 3.0 I am no longer able to create a virtual machine that is backed by LVM storage on my two Arch machines. This is the error in virt-manager: Unable to complete install: 'An error occurred, but the cause is unknown' Traceback (most recent call last): File "/usr/share/virt-manager/virtManager/asyncjob.py", line 88, in cb_wrapper callback(asyncjob, *args, **kwargs) File "/usr/share/virt-manager/virtManager/create.py", line 2288, in _do_async_install guest.start_install(meter=meter) File "/usr/share/virt-manager/virtinst/guest.py", line 461, in start_install doboot, transient) File "/usr/share/virt-manager/virtinst/guest.py", line 396, in _create_guest self.domain = self.conn.createXML(install_xml or final_xml, 0) File "/usr/lib/python2.7/site-packages/libvirt.py", line 3773, in createXML if ret is None:raise libvirtError('virDomainCreateXML() failed', conn=self) libvirtError: An error occurred, but the cause is unknown I originally encountered the problem when running my Ansible modules for libvirt in https://github.com/ansible-provisioning/ansible-provisioning , so the issue is not virt-manager specific. Steps to reproduce in virt-manager (1.4.0-3): - create a new VM - choose import existing disk image - create a new logical volume when browsing to find the existing image path or select a lv that was manually created before. - click forward - click forward - click finish When using qcow2 storage, both virt-manager and my modules work fine. This was also working on previous versions of libvirt. I do not see any changes in compilation flags in the Arch packages. Is there anything I can do to help diagnose this issue? Greetings, Jeroen