Internal Server Error

The server has either erred or is incapable of performing the requested operation.

Traceback (most recent call last):
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/25fef2553b936881/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1535, in __call__
    rv = self.handle_exception(request, response, e)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/25fef2553b936881/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1529, in __call__
    rv = self.router.dispatch(request, response)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/25fef2553b936881/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/25fef2553b936881/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/25fef2553b936881/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/25fef2553b936881/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/apps/s~wawosca/19.453511391276844003/main.py", line 466, in get
    self.redirect(self.request.referrer)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/25fef2553b936881/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 608, in redirect
    response=self.response)
  File "/base/alloc/tmpfs/dynamic_runtimes/python27g/25fef2553b936881/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1764, in redirect
    if uri.startswith(('.', '/')):
AttributeError: 'NoneType' object has no attribute 'startswith'