While running masakari test this unexpected API error occurred, it says to open a bug
2023-01-20-21:01:31 keystoneauth.session DEBUG RESP: [500] Connection: close Content-Length: 224 Content-Type: application/json; charset=UTF-8 Date: Fri, 20 Jan 2023 21:01:30 GMT OpenStack-API-Version: compute 2.72 Server: Apache/2.4.41 (Ubuntu) Vary: OpenStack-API-Version,X-OpenStack-Nova-API-Version X-OpenStack-Nova-API-Version: 2.72 x-compute-request-id: req-7538e84d-39fb-4146-98f8-43d446b58398 x-openstack-request-id: req-7538e84d-39fb-4146-98f8-43d446b58398
2023-01-20-21:01:31 keystoneauth.session DEBUG RESP BODY: {"computeFault": {"code": 500, "message": "Unexpected API Error. Please report this at http://bugs.launchpad.net/nova/ and attach the Nova API log if possible.\n<class 'neutronclient.common.exceptions.ServiceUnavailable'>"}}
Logs
https://oil-jenkins.canonical.com/artifacts/72b27e0d-2ef1-4b72-9d0c-b29407bfa746/generated/generated/openstack/juju-crashdump-openstack-2023-01-20-21.02.27.tar.gz
It looks your environment is not able to call the Neutron API, hence the exception.
Sorry, but this is not a nova bug report, hence me closing it.