Hi @Retired_mod , I tried the region based gcp databricks url as well and this is also failing with invalid URL error. 

URL: https://us-east4.gcp.databricks.com/api/2.0/clusters/list-zones

Response:

{
  "error_code": "400",
  "message": "Invalid URL. Please use the per-workspace URL and try again."
}

Also I have checked all the necessary permissions for SA and it is already available.

One more thing - on GCP workspace URL, list-node-types REST call is working fine and giving the expected result, but list-zones is failing.

Thanks