Neutron L3 Error

2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task [req-6184915f-779f-48b5-9091-8b6de7ca2be7 - - - - -] Error during L3NATAgentWithStateReport.periodic_sync_routers_task
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task Traceback (most recent call last):
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/oslo_service/periodic_task.py", line 220, in run_periodic_tasks
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     task(self, context)
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/neutron/agent/l3/agent.py", line 552, in periodic_sync_routers_task
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     self.fetch_and_sync_all_routers(context, ns_manager)
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/osprofiler/profiler.py", line 154, in wrapper
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     return f(*args, **kwargs)
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/neutron/agent/l3/agent.py", line 563, in fetch_and_sync_all_routers
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     router_ids = self.plugin_rpc.get_router_ids(context)
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/neutron/agent/l3/agent.py", line 114, in get_router_ids
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     return cctxt.call(context, 'get_router_ids', host=self.host)
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/neutron/common/rpc.py", line 138, in call
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     return self._original_context.call(ctxt, method, **kwargs)
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/client.py", line 169, in call
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     retry=self.retry)
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/oslo_messaging/transport.py", line 97, in _send
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     timeout=timeout, retry=retry)
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/oslo_messaging/_drivers/amqpdriver.py", line 464, in send
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     retry=retry)
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task   File "/usr/lib/python2.7/site-packages/oslo_messaging/_drivers/amqpdriver.py", line 455, in _send
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task     raise result
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task TypeError: 'NoneType' object is not iterable
2016-12-08 16:07:29.747 17923 ERROR oslo_service.periodic_task Traceback (most recent call last):