I have the same error message now when trying to create a USE_SCHEMA grant for a service principal as in https://registry.terraform.io/providers/databricks/databricks/latest/docs/resources/grant#schema-gra... . I create a new service principal and then assign the grant. The creation works, the assignement doesn't. So the databricks credentials do work. Also, there is no AWS IAM role involved. I again tried both with account level and workspace level provider.