gitlab_branch: Invalid resource ID format error when updating branch

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Bug Report

The gitlab_branch resource's Update function incorrectly reads the resource ID from the plan instead of state, causing an "Invalid resource ID format" error when updating branches. The ID is empty ('') in the plan during updates, but it should be read from state (as Read and Delete functions do).

This bug was introduced when migrating from SDK v2 to the Plugin Framework. The old SDK version correctly used d.Id() which reads from state, but the new Plugin Framework version reads from req.Plan instead of req.State. 28bb3739

Relevant Terraform Configuration 

resource "gitlab_branch" "foo" {
  count               = var.foo == "foo" || var.bar ? 1 : 0
  name                = "foo"
  ref                 = "master"
  project             = gitlab_project.project.id
  keep_on_destroy     = false

  lifecycle {
    ignore_changes = [
      ref
    ]
  }
}

Relevant Terraform Command 

terraform plan
# or
terraform apply

Relevant Log Output

Error message: 
Error: Invalid resource ID format
│
│   with module.project-example.gitlab_branch.foo[0],
│   on ../modules/foo/main.tf line 123, in resource "gitlab_branch" "foo":
│  289: resource "gitlab_branch" "foo" {
│
│ The resource ID '' has an invalid format in Read. Error: Unexpected ID
│ format (""). Expected <part1>:<part2>
Terraform plan output: 
# module.project-example.gitlab_branch.foo[0] will be updated in-place
  ~ resource "gitlab_branch" "foo" {
      ~ can_push            = true -> (known after apply)
      ~ commit              = [
          - {
              - author_email    = "user@example.com" -> null
              - author_name     = "Example User" -> null
              - authored_date   = "2025-12-05T15:28:05Z" -> null
              - committed_date  = "2025-12-05T15:28:05Z" -> null
              - committer_email = "user@example.com" -> null
              - committer_name  = "Example User" -> null
              - id              = "abc123def456..." -> null
              - message         = <<-EOT
                    Merge branch 'feature-branch' into 'foo'
                    ...
                EOT -> null
              - parent_ids      = [
                  - "parent1...",
                  - "parent2...",
                ] -> null
              - short_id        = "abc123de" -> null
              - title           = "Merge branch 'feature-branch' into 'foo'" -> null
            },
        ] -> (known after apply)
      ~ default             = true -> (known after apply)
      ~ developer_can_merge = true -> (known after apply)
      ~ developer_can_push  = false -> (known after apply)
      ~ id                  = "12345678:foo" -> (known after apply)
      + keep_on_destroy     = false
      ~ merged              = false -> (known after apply)
        name                = "foo"
      ~ protected           = true -> (known after apply)
      ~ web_url             = "https://gitlab.com/group/project/-/tree/foo" -> (known after apply)
        # (1 unchanged attribute hidden)
    }

Expected behavior: The Update function should read the ID from req.State (like Read and Delete do), not from req.Plan. The ID is immutable (computed from project and name which both have RequiresReplace()), so it should always be read from state.

Comparison with other functions:

  • Read function (line 241): req.State.Get(ctx, &data) ✅
  • Delete function (line 309): req.State.Get(ctx, &data) ✅
  • Update function (line 276): req.Plan.Get(ctx, &data) ❌

Old SDK v2 version (working): The old version correctly used d.Id() which reads from state:

func resourceGitlabBranchUpdate(ctx context.Context, d *schema.ResourceData, meta any) diag.Diagnostics {
	return resourceGitlabBranchRead(ctx, d, meta)  // Read uses d.Id() from state
}

Additional Details

  • GitLab Terraform Provider Version: > 18.5.0
  • GitLab Instance Version: 18.7.0-pre
  • Terraform Version: OpenTofu v1.10.7
  • License Tier: enterprise
Edited by Nathan Gille