Traceback (most recent call last):
  File "/usr/share/software-center/softwarecenter/backend/channel.py", line 157, in _check_for_channel_updates_timer
    self.backend.update_xapian_index()
  File "/usr/share/software-center/softwarecenter/backend/aptd.py", line 137, in update_xapian_index
    axi.update_async(True, True)
  File "/usr/lib/pymodules/python2.7/dbus/proxies.py", line 68, in __call__
    return self._proxy_method(*args, **keywords)
  File "/usr/lib/pymodules/python2.7/dbus/proxies.py", line 140, in __call__
    **keywords)
  File "/usr/lib/pymodules/python2.7/dbus/connection.py", line 630, in call_blocking
    message, timeout)
DBusException: org.freedesktop.DBus.Python.PermissionDeniedError: Permission denied by policy