It turns out this problem is caused by using:
router_scheduler_driver = neutron.scheduler.l3_agent_scheduler.AZLeastRoutersScheduler
and an unexpected NoneType returned by _get_routers_can_schedule called from within _schedule_ha_routers_to_additional_agent.
It turns out this problem is caused by using:
router_ scheduler_ driver = neutron. scheduler. l3_agent_ scheduler. AZLeastRoutersS cheduler
and an unexpected NoneType returned by _get_routers_ can_schedule called from within _schedule_ ha_routers_ to_additional_ agent.