Network creation fails with OVN

Issue

• Unable to create private network with ovn as SDN.

• Creation of the network results in the below error.

  (overcloud) [hostname@director ~]$ openstack network create --provider-network-type vlan --provider-physical-network datacentre --provider-segment 501 501-Proj-Infra
  Error while executing command: HttpException: 500, Request Failed: internal server error while processing your request.
  

• The network agent list also results in Internal Server error

  (overcloud) [hostname@director ~]$ openstack network agent list
  HttpException: 500: Server Error for url: https://osp.hostname:13696/v2.0/agents, Request Failed: internal server error while processing your request.