def messageArg(self):
        """Respond with an HTTP 500 and a custom message."""
        message = (
            "If you construct an HTTPError with a 'message' "
            'argument, it wil be placed on the error page '
            '(underneath the status line by default).'
        )
        raise cherrypy.HTTPError(500, message=message)
Respond with an HTTP 500 and a custom message.
cherrypy/tutorial/tut10_http_errors.py