Couldn't add "network interface" in virt-manager

view story

https://bbs.archlinux.org – I'm using arch 64bits linux. Reproduce steps1. start libvirtd 2. launch virt-manager3. From menu, "Edit" -> "connection details" -> "network interface"There is no interface showing in the left side.And if press "+" button to add an interface, I get following error:Error creating interface: 'Could not define interface: internal error could not get interface XML description: unspecified error - aug_save failed'Traceback (most recent call last):  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 96, in cb_wrapp (HowTos)