Can't upgrade from 0.11.14 to 0.13.0 with version 3 statefile containing remote state data resource

[alisdair]

Terraform Version

Using the branch from #25861

Terraform v0.13.1-dev

Terraform Configuration Files

data "terraform_remote_state" "test" {
  backend = "remote"

  config = {
    organization = "my-tfc-org"
    workspaces = {
      name = "some-tfc-workspace"
    }
  }
}

Debug Output

Log gist

Expected Behavior

An empty plan.

Actual Behavior

$ terraform plan
Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.


Error: cannot decode dynamic from flatmap

$

Steps to Reproduce

1. Create a config with a Terraform Cloud remote state data source block pointing to a workspace
2. Run terraform init and terraform apply with Terraform 0.11.14 to create a state file
3. Run terraform plan with Terraform 0.13.1-dev (after addrs: Fix LegacyString for builtin providers #25861 is merged, or using that branch, or it'll panic)

Additional Context

This works with Terraform 0.12.28. The failure is in attempting to decode the dynamic config block from the flatmap in the state file. From looking at the v0.12 branch, I can't see how this used to work, nor any reason why it should only start failing with 0.13.

References

Found when investigating the fix for #25803.

[apparentlymart]

In your "steps to reproduce" it seems like you went directly from 0.11.14 to 0.13.1 without applying with a 0.12.x release first. Does this still fail if you upgrade only one major version at a time?

Our typical policy is that we don't support skipping major releases, because that creates the risk of missing out on upgrade steps that were present in an earlier release but no longer present in the current release. So if this is "fixed" by running terraform apply with 0.12.x first then I'd be inclined to consider it a "won't fix".

[alisdair]

That's correct—running a terraform apply with 0.12 upgrades the state file and 0.13 is then able to use it. The policy makes sense to me, closing!

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

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