Error when trying to add another Compute node to the stack.

Issue

• Scale out fails with:

DeploymentError: Heat Stack update failed.

END return value: 1
 Resource CREATE failed: Error: resources[8].resources.NetworkDeployment: Deployment to server failed: deploy_status_code: Deployment exited with non-zero status code: 1
2020-10-13 20:44:20Z [Compute]: UPDATE_FAILED  resources.Compute: Resource CREATE failed: Error: resources[8].resources.NetworkDeployment: Deployment to server failed: deploy_status_code: Deployment exited with non-zero status code: 1
2020-10-13 20:44:20Z [overcloud]: UPDATE_FAILED  Resource UPDATE failed: resources.Compute: Resource CREATE failed: Error: resources[8].resources.NetworkDeployment: Deployment to server failed: deploy_status_code: Deployment exited with non-zero status code: 1

 Stack overcloud UPDATE_FAILED 

overcloud.Compute.8.NetworkDeployment:
  resource_type: OS::TripleO::SoftwareDeployment
  physical_resource_id: 84277f9f-8a4f-4005-a946-82df6f3d843c
  status: CREATE_FAILED
  status_reason: |
    Error: resources.NetworkDeployment: Deployment to server failed: deploy_status_code : Deployment exited with non-zero status code: 1

• /var/log/messages in the new compute node shows this:

Oct 14 10:00:28 overcloud-compute-8 os-collect-config: [2020/10/14 09:59:05 AM] [INFO] Using config file at: /etc/os-net-config/config.json
Oct 14 10:00:28 overcloud-compute-8 os-collect-config: [2020/10/14 09:59:05 AM] [INFO] Using mapping file at: /etc/os-net-config/mapping.yaml
Oct 14 10:00:28 overcloud-compute-8 os-collect-config: [2020/10/14 09:59:05 AM] [INFO] Ifcfg net config provider created.
Oct 14 10:00:28 overcloud-compute-8 os-collect-config: [2020/10/14 09:59:05 AM] [WARNING] Config file failed schema validation at network_config/1:
Oct 14 10:00:28 overcloud-compute-8 os-collect-config: {'persist_mapping': False, 'domain': [], 'dns_servers': ['x.x.x.x', '8.8.8.8'], 'name': 'br-ex', 'members': [{'members': [{'type': 'interface', 'name': 'nic2', 'primary': True}, {'type': 'interface', 'name': 'nic3'}], 'type': 'ovs_bond', 'name': 'bond1', 'ovs_options': 'bond_mode=active-backup'}, {'type': 'vlan', 'addresses': [{'ip_netmask': 'x.x.x.x/24'}], 'vlan_id': 4010}, {'type': 'vlan', 'addresses': [{'ip_netmask': 'x.x.x.x/24'}], 'vlan_id': 4012}, {'type': 'vlan', 'addresses': [{'ip_netmask': 'x.x.x.x/24'}], 'vlan_id': 2015}], 'nic_mapping': None, 'type': 'ovs_bridge'} is not valid under any of the given schemas
Oct 14 10:00:28 overcloud-compute-8 os-collect-config: Sub-schemas tested and not matching:
Oct 14 10:00:28 overcloud-compute-8 os-collect-config: - items/oneOf/ovs_bridge/additionalProperties: Additional properties are not allowed ('domain' was unexpected)