We use ovirt-engine 4.5.5-1.el8 and for us the following did the trick:

1. First you have to decide, if you need the ovn/ovs functionality. This is a cluster level decision!
• If needed, you need to have a functional (You can test it) external network provider configured (Administration -> Providers -> External Network Provider) ?? As far as I know, a default “ovirt-provider-ovn” is already present in each installation
• Then in the cluster option you choose the “Default Network Provider”.
  If you don’t need OVS/OVN, then select “No Default Provider”, else select the one you need
• If you change here anything, ovirt want you to reinstall all your hosts in this cluster!
2. Then, replace the ansible file in your ovirt-engine:
• /usr/share/ovirt-engine/ansible-runner-service-project/project/roles/ovirt-provider-ovn-driver/tasks/configure.yml
• The new version can be found here:
  https://github.com/oVirt/ovirt-engine/blob/master/packaging/ansible-runner-service-project/project/roles/ovirt-provider-ovn-driver/tasks/configure.yml
  as far as I can tell, only the last line (when statement) changes

Probably, only ppl who don’t need ovn/ovs had (Setting: “No Default Provider”) had this problem.

3. Reinstall the hosts
   
   

As always, know what you do, before you anything.