How to fix Error: Unknown configuration attributes in Terraform

Run terraform version to see what versions you have installed:

terraform version

This shows your Terraform version and all required providers. Compare these against your .terraform/versions lock file or required_providers block in your code. If versions differ significantly from your configuration expectations, this is likely the root cause.

The error message will typically specify which attribute is unknown. For example:

Error: Unsupported argument

  on main.tf line 5, in resource "aws_instance" "example":
   5:   deprecated_field = "value"

An argument named "deprecated_field" is not expected here.

Make note of the exact attribute name and resource type mentioned. Check the provider's documentation to see if this attribute exists in your provider version or if it was renamed/removed.

Edit your terraform block to pin provider versions if you want stability:

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"  # Pin to 5.x series
    }
  }
}

Then run:

terraform init -upgrade

This initializes Terraform and upgrades providers to match your constraints. If you want to downgrade instead, update the version constraint to a lower version and repeat.

Check the provider documentation for the correct attribute name and update your configuration. For example, if 'deprecated_field' was renamed to 'new_field', update your code:

# Before (causes error)
resource "aws_instance" "example" {
  deprecated_field = "value"
}

# After (correct)
resource "aws_instance" "example" {
  new_field = "value"
}

If the attribute was removed entirely, delete it from your configuration.

If you've updated your configuration but still encounter the error, your state file may be out of sync. First, back up your state:

terraform state pull > backup.tfstate

Then remove the problematic resource from state (if it's safe to do so):

terraform state rm aws_instance.example

Finally, reinitialize Terraform:

terraform init
terraform plan

This allows Terraform to re-create the resource with the current provider schema. Only use this if the resource can be safely recreated.

Visit the provider's official documentation and release notes to understand what changed between versions. For example, for AWS provider:

https://registry.terraform.io/providers/hashicorp/aws/latest/docs

Look at the CHANGELOG to see what attributes were added, removed, or renamed in the versions between your old and new provider. This helps you understand whether to update your code or adjust provider versions.