jesseduffield/lazygit · error

Expected exactly one merge commit with hash %s

Error message

Expected exactly one merge commit with hash %s

What it means

Returned by dropMergeCommit when dropping a merge commit during a rebase: it looks for exactly one todo with command 'merge', flag '-C', and the given hash. If none or several match (typically zero, because the merge is recorded differently or already handled), the drop is refused since deleting the wrong line would corrupt the plan.

Source

Thrown at pkg/utils/rebase_todo.go:328

	todos, err := ReadRebaseTodoFile(fileName, commentChar)
	if err != nil {
		return err
	}

	newTodos, err := dropMergeCommit(todos, hash)
	if err != nil {
		return err
	}

	return WriteRebaseTodoFile(fileName, newTodos, commentChar)
}

func dropMergeCommit(todos []todo.Todo, hash string) ([]todo.Todo, error) {
	isMerge := func(t todo.Todo) bool {
		return t.Command == todo.Merge && t.Flag == "-C" && equalHash(t.Commit, hash)
	}
	if lo.CountBy(todos, isMerge) != 1 {
		return nil, fmt.Errorf("Expected exactly one merge commit with hash %s", hash)
	}

	_, idx, _ := lo.FindIndexOf(todos, isMerge)
	return slices.Delete(todos, idx, idx+1), nil
}

View on GitHub (pinned to c477a2959b)

Solutions

1. Open .git-rebase-todo and confirm a 'merge -C <hash>' line exists with the exact hash shown; edit manually if the encoding differs
2. If the merge was already applied, refresh/restart the rebase view before dropping
3. Upgrade git so rebase todos use the merge -C form lazygit expects

# verify the exact merge line exists before dropping
grep -cE "^merge -C ${FULL_HASH}" .git/rebase-merge/git-rebase-todo  # want exactly 1

Catch, show the expected 'merge -C <hash>' form to the user, and offer to open the todo file for manual editing instead of retrying blind.

When it happens

Trigger: Dropping a merge commit from lazygit's commits view during an interactive rebase where the todo file lacks a 'merge -C <hash>' line for it (older git writing 'merge' differently, the merge already applied, or an externally edited todo).

Common situations: Rebases created by older git versions or other tools that don't emit 'merge -C'; attempting to drop a merge whose todo entry was already consumed; hash format mismatches (full vs abbreviated) in the todo file.

Related errors

• Todo %s not found in git-rebase-todo
• Expected exactly one original hash, found %d
• Expected exactly one fixup hash, found %d
• Cannot start interactive rebase: the HEAD commit is a merge
• index outside of range of commits

AI-assisted analysis of jesseduffield/lazygit@c477a2959b (2026-08-15). Data as JSON: /api/errors/87435c8c71003f19. Report an issue: GitHub.