env-var.sh

terraform {
  backend "local" {}
  encryption {
    key_provider "pbkdf2" "my_passphrase" {
      passphrase = "something very secret and over 16 chars long"
    }
    method "aes_gcm" "my_method" {
      keys = key_provider.pbkdf2.my_passphrase
    }

    state {
      method = method.aes_gcm.my_method
      fallback{} # Remove after the migration is complete.
    }
  }
}

GitHub-ci-error.txt

$ ./tofu apply -auto-approve

OpenTofu used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  + create

OpenTofu will perform the following actions:

  # local_file.hello_local_file will be created
  + resource "local_file" "hello_local_file" {
      + content              = "Hello terraform local!"
      + content_base64sha256 = (known after apply)
      + content_base64sha512 = (known after apply)
      + content_md5          = (known after apply)
      + content_sha1         = (known after apply)
      + content_sha256       = (known after apply)
      + content_sha512       = (known after apply)
      + directory_permission = "0777"
      + file_permission      = "0777"
      + filename             = "./hello_local_file.txt"
      + id                   = (known after apply)
    }

Plan: 1 to add, 0 to change, 0 to destroy.
local_file.hello_local_file: Creating...
local_file.hello_local_file: Creation complete after 0s [id=87854c876545c68a54349a141d2a023ef503e9b3]
╷
│ Error: Failed to save state
│
│ Error saving state: encryption of "state" is enforced, and therefore requires a method to be provided
╵
╷
│ Error: Failed to create local state file
│
│ Error creating local state file for recovery: encryption of "state" is enforced, and therefore requires a method to be provided
╵
╷
│ Error: Failed to serialize state
│
│ Failed to save state after apply.
│
│ Error serializing state: encryption of "state" is enforced, and therefore requires a method to be provided
│
│ A catastrophic error has prevented OpenTofu from persisting the state file or creating a backup. Unfortunately this means that the record of any resources created during this
│ apply has been lost, and such resources may exist outside of OpenTofu's management.
│
│ For resources that support import, it is possible to recover by manually importing each resource using its id from the target system.
│
│ This is a serious bug in OpenTofu and should be reported.
│
╵
╷
│ Error: Failed to persist state to backend
│
│ The errors shown above prevented OpenTofu from writing the updated state to
│ the configured backend and from creating a local backup file. As a fallback,
│ the raw state data is printed above as a JSON object.
│
│ To retry writing this state, copy the state data (from the first { to the last } inclusive) and save it into a local file called errored.tfstate, then run the following
│ command:
│     tofu state push errored.tfstate

main.tf

resource "local_file""hello_local_file" {
  content = "Hello terraform local!"
  filename = "${path.module}/hello_local_file.txt"
}