Terraform "Unsupported block type" in CI

By Kaveh Alemi·Latchkey

A configuration declares a nested block the resource/provider schema does not define -- a misspelled block, a block from a different resource, or one removed/renamed in a provider version.

What this error means

validate/plan fails with "Unsupported block type", naming the block. It often surfaces after a provider major upgrade that restructured a block, or copy-pasting a block onto the wrong resource.

terraform

Error: Unsupported block type

  on main.tf line 9, in resource "aws_instance" "app":
   9:   ebs_block_device {

Blocks of type "ebs_block_device" are not expected here.

Common causes

Block not valid for this resource

The nested block belongs to a different resource, or is misspelled, so the schema does not recognize it.

Block restructured in a provider upgrade

A provider major version may move a nested block to a separate resource or rename it, breaking old config.

How to fix it

Use the correct block for the schema

Check the provider docs for the resource version and use the supported block (or its replacement resource).

main.tf

# newer aws provider: use the standalone resource
resource "aws_ebs_volume" "data" {
  availability_zone = "us-east-1a"
  size              = 100
}

resource "aws_volume_attachment" "data" {
  device_name = "/dev/sdh"
  volume_id   = aws_ebs_volume.data.id
  instance_id = aws_instance.app.id
}

Fix typos and misplacement

Confirm the block name matches the resource schema exactly.
Ensure the block is inside the resource that defines it.
Pin the provider version so the schema is predictable.

How to prevent it

Read provider upgrade guides before bumping major versions.
Run terraform validate in CI to catch unsupported blocks.
Pin provider versions for a stable schema.

Frequently asked questions

What causes ""Unsupported block type""?