Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.6/dbus/connection.py", line 579, in msg_reply_handler
    *message.get_args_list()))
  File "/usr/share/software-center/softwarecenter/backend/aptd.py", line 170, in _on_trans_error
    raise error
DBusException: org.freedesktop.DBus.Error.UnknownMethod: Method "Set" with signature "sss" on interface "org.freedesktop.DBus.Properties" doesn't exist