400 parameter validation failed for Terraform with Proxmox

Dec 11, 2022

The main terraform provider for proxmox is not very polished. It works, but doesn’t appear to perform any validation of your inputs, and also does a terrible job of communicating errors thrown by proxmox. Consequently, any time you make a mistake in your resource, you’re likely to see an extremely unhelpful message that says:

400 Parameter Validation failed

When this happens, add pm_debug = true to your provider configuration:

provider "proxmox" {
  pm_debug = true

and run TF_LOG_TRACE=TRACE terraform apply to get detailed logs from terraform. The actual problem with your resource will be somethere in the output.