pcottle/learnGitBranching · error · GitError

fatal: HEAD does not point to a branch

Error message

fatal: HEAD does not point to a branch

What it means

git branch -m <newname> (single-arg form) renames the current branch, which requires HEAD to point at a branch. If HEAD is detached (points at a commit), this fatal GitError is thrown.

Source

Thrown at src/js/git/commands.js:541

      if (commandOptions['--contains']) {
        args = commandOptions['--contains'];
        command.validateArgBounds(args, 1, 1, '--contains');
        engine.printBranchesWithout(args[0]);
        return;
      }

      if (commandOptions['-m'] || commandOptions['-M'] || commandOptions['--move']) {
        var moveArgs = commandOptions['-m'] || commandOptions['-M'] || commandOptions['--move'];
        var force = !!commandOptions['-M'];
        args = moveArgs.concat(generalArgs);
        command.validateArgBounds(args, 1, 2, '-m');

        var oldName, newName;
        if (args.length === 1) {
          // git branch -m <newname>: rename current branch
          var headTarget = engine.HEAD.get('target');
          if (headTarget.get('type') !== 'branch') {
            throw new GitError({
              msg: intl.todo('fatal: HEAD does not point to a branch')
            });
          }
          oldName = headTarget.get('id');
          newName = args[0];
        } else {
          // git branch -m <oldname> <newname>
          oldName = args[0];
          newName = args[1];
        }

        engine.renameBranch(oldName, newName, force);
        return;
      }

      if (commandOptions['-f'] || commandOptions['--force']) {
        args = commandOptions['-f'] || commandOptions['--force'];
        args = args.concat(generalArgs);

View on GitHub (pinned to 5b09d0ff96)

Solutions

  1. Use the two-arg form: git branch -m <old> <new>
  2. Reattach HEAD (git checkout main) before renaming

Example fix

// before
git checkout C1; git branch -m newmain
// after
git checkout C1; git branch -m main newmain
Defensive patterns

Strategy: validation

Validate before calling

if (args.length === 1 && engine.HEAD.get('target').get('type') !== 'branch') { use two-arg form }

Type guard

function headOnBranch(engine) { return engine.HEAD.get('target').get('type') === 'branch'; }

Prevention

When it happens

Trigger: git checkout C1 then git branch -m renamed.

Common situations: Renaming while inspecting an old commit; forgetting you detached earlier.

Related errors

AI-assisted analysis of pcottle/learnGitBranching@5b09d0ff96 (2026-08-27). Data as JSON: /api/errors/a835afc78874dde3. Report an issue: GitHub.