BUG: Error launching manager: 'NoneType' object has no attribute 'get_default_storage_format'

Error launching manager: 'NoneType' object has no attribute 'get_default_storage_format'

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/engine.py", line 889, in _do_show_create
    self._get_create_dialog().show(src.topwin, uri)
  File "/usr/share/virt-manager/virtManager/create.py", line 170, in show
    self.reset_state(uri)
  File "/usr/share/virt-manager/virtManager/create.py", line 393, in reset_state
    self.addstorage.reset_state()
  File "/usr/share/virt-manager/virtManager/addstorage.py", line 196, in reset_state
    fmt = self.conn.get_default_storage_format()
AttributeError: 'NoneType' object has no attribute 'get_default_storage_format'