Terraform http staus code 400

i would like to use terraform for deploying new VMs.
each time i use the opennebula providers. I just get the following error:
Error: GOCA client error [RESPONSE_HTTP]: http status code: 400

on tmpl_info.tf line 13, in data “opennebula_template” “tmpl_info”:
13: data “opennebula_template” “tmpl_info” {
did anybody has a hint, what is the cause of this error?

there ist in the terraform logs the error:
plugin.stdio: received EOF, stopping recv loop: err=“rpc error: code = Unimplemented desc = unknown service plugin.GRPCStdio”