500 HTTP error on login

On staging server, on failed login the API returns a 500 HTTP error:

POST /ThreatKB/login
{"email":"jgemic@inquest.net","password":"*******"}

AttributeError
AttributeError: 'AnonymousUserMixin' object has no attribute 'id'

Traceback (most recent call last)
File "/opt/threatkb/env/lib/python2.7/site-packages/flask/app.py", line 1701, in __call__
                                'Flask.blueprints instead'), stacklevel=2)
        return self.blueprints
 
    def __call__(self, environ, start_response):
        """Shortcut for :attr:`wsgi_app`."""
        return self.wsgi_app(environ, start_response)
File "/opt/threatkb/env/lib/python2.7/site-packages/flask/app.py", line 1689, in wsgi_app
        """
        with self.request_context(environ):
            try:
                response = self.full_dispatch_request()
            except Exception, e:
                response = self.make_response(self.handle_exception(e))
            return response(environ, start_response)
 
    @property
    def modules(self):
        from warnings import warn
File "/opt/threatkb/env/lib/python2.7/site-packages/flask/app.py", line 1687, in wsgi_app
                               a list of headers and an optional
                               exception context to start the response
        """
        with self.request_context(environ):
            try:
                response = self.full_dispatch_request()
            except Exception, e:
                response = self.make_response(self.handle_exception(e))
            return response(environ, start_response)
 
    @property
File "/opt/threatkb/env/lib/python2.7/site-packages/flask/app.py", line 1360, in full_dispatch_request
            request_started.send(self)
            rv = self.preprocess_request()
            if rv is None:
                rv = self.dispatch_request()
        except Exception, e:
            rv = self.handle_user_exception(e)
        response = self.make_response(rv)
        response = self.process_response(response)
        request_finished.send(self, response=response)
        return response
 
File "/opt/threatkb/env/lib/python2.7/site-packages/flask/app.py", line 1262, in handle_user_exception
        if handlers is not None:
            blueprint_handlers = handlers.get(None, ())
        app_handlers = self.error_handler_spec[None].get(None, ())
        for typecheck, handler in chain(blueprint_handlers, app_handlers):
            if isinstance(e, typecheck):
                return handler(e)
 
        raise exc_type, exc_value, tb
 
    def handle_exception(self, e):
        """Default exception handling that kicks in when an exception
File "/opt/threatkb/app/routes/error_handling.py", line 24, in handle_exception
 
    stacktrace = "%s" % (
        re.sub(r'\"[^\"]+\/([^\"]+)', r"\1", traceback.format_exc().replace("\n", "<BR>").replace(" ", "&nbsp;")))
    err = Error(
        stacktrace=traceback.format_exc(),
        user_id=current_user.id,
        remote_addr=request.remote_addr,
        args=str(request.args.to_dict(flat=False)),
        method=request.method,
        route=request.url_rule
    )
File "/opt/threatkb/env/lib/python2.7/site-packages/werkzeug/local.py", line 347, in __getattr__
            return []
 
    def __getattr__(self, name):
        if name == '__members__':
            return dir(self._get_current_object())
        return getattr(self._get_current_object(), name)
 
    def __setitem__(self, key, value):
        self._get_current_object()[key] = value
 
    def __delitem__(self, key):
AttributeError: 'AnonymousUserMixin' object has no attribute 'id'