The server encountered an unexpected condition which prevented it from fulfilling the request.
Traceback (most recent call last): File "/usr/local/lib/python2.7/dist-packages/cherrypy/_cprequest.py", line 670, in respond response.body = self.handler() File "/usr/local/lib/python2.7/dist-packages/cherrypy/lib/encoding.py", line 220, in __call__ self.body = self.oldhandler(*args, **kwargs) File "/usr/local/lib/python2.7/dist-packages/cherrypy/_cpdispatch.py", line 60, in __call__ return self.callable(*self.args, **self.kwargs) File "/dist_test/infra/server.py", line 127, in trace dur=self._delta_us(task['complete_timestamp'] - task['start_timestamp']), TypeError: unsupported operand type(s) for -: 'datetime.datetime' and 'NoneType'