Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/defer/__init__.py", line 388, in _next
    self.result = callback(self.result, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/defer/utils.py", line 64, in <lambda>
    deferred.add_errback(lambda error: dbus_errback(error.value))
  File "/usr/lib/pymodules/python2.7/dbus/service.py", line 664, in <lambda>
    keywords[error_callback] = lambda exception: _method_reply_error(connection, message, exception)
  File "/usr/lib/pymodules/python2.7/dbus/service.py", line 282, in _method_reply_error
    contents = exception.get_dbus_message()
  File "/usr/lib/pymodules/python2.7/dbus/exceptions.py", line 59, in get_dbus_message
    s = Exception.__str__(self)
UnicodeEncodeError: 'ascii' codec can't encode characters in position 29-42: ordinal not in range(128)