It seems to be known that in case of a Windows GUI app that isn’t connected to a console sys.stderr can be None. See the Note on http://docs.python.org/py3k/library/sys.html: Under some conditions stdin, stdout and stderr as well as the original values __stdin__, __stdout__ and __stderr__ can be None. It is usually the case for Windows GUI apps that aren’t connected to a console and Python apps started with pythonw.
In combination with logging this leads to an issue similar to issue #5971. In my case sys.stderr is None and File: lib\logging\__init__.py, Class: Handler, Method: handleError raises AttributeError: 'NoneType' object has no attribute 'write'.
A 'simple' solution would be to check if sys.stderr is not None. In case it is None handleError must not call traceback.print_exception() and not directly write to sys.stderr.