windmill-labs/windmill · error · Error

You are on working branch \`${currentBranch}\`, which is not

Error message

You are on working branch \`${currentBranch}\`, which is not a base branch. Pass --from-branch <base> to base the fork on a base branch and rename this branch onto the fork branch, or check out a base branch and run \`wmill workspace fork\` to create a fresh fork branch.

What it means

`wmill workspace fork` refuses to create a fork when the current git working branch is not one of the configured base branches and the command is running non-interactively (no TTY or --yes). Because it cannot prompt the user to confirm basing/rename, it throws to avoid silently forking off an unexpected branch.

Source

Thrown at cli/src/commands/workspace/fork.ts:436

  - Use the Merge UI from the forked workspace home page
  - Use git: ` + colors.white(`git checkout ${clonedBranchName} && git merge ${newBranchName} && wmill sync push`) + `
  See: https://www.windmill.dev/docs/advanced/workspace_forks`);
}

/**
 * When `wmill workspace fork` is run from a non-base working branch, confirm
 * the user wants to turn it into a fork branch, and resolve which base branch
 * the fork should be linked to. Throws in non-interactive mode (where the user
 * must pass `--from-branch <base>` instead).
 */
async function resolveWorkingBranchBase(
  config: Awaited<ReturnType<typeof readConfigFile>>,
  opts: { yes?: boolean },
  currentBranch: string,
): Promise<string> {
  const interactive = process.stdin.isTTY && opts.yes !== true;
  if (!interactive) {
    throw new Error(
      `You are on working branch \`${currentBranch}\`, which is not a base branch. ` +
      `Pass --from-branch <base> to base the fork on a base branch and rename this branch onto the fork branch, ` +
      `or check out a base branch and run \`wmill workspace fork\` to create a fresh fork branch.`,
    );
  }

  const { Select } = await import("@cliffy/prompt/select");
  const proceed = await Select.prompt({
    message: `You're on working branch \`${currentBranch}\`, not a base branch. Base a fork on it and rename it onto the fork branch?`,
    options: [
      { name: "Yes, base the fork on this branch and rename it", value: "yes" },
      { name: "No, cancel", value: "no" },
    ],
  });
  if (proceed !== "yes") {
    throw new Error("Fork cancelled. Check out a base branch to create a fresh fork branch instead.");
  }

View on GitHub (pinned to e474e8803c)

Solutions

Pass `--from-branch <base>` so the fork is explicitly based on a base branch
Check out a base branch before running `wmill workspace fork` to create a fresh fork branch
Rename the current branch onto the fork branch, then re-run
Run the command in an interactive terminal without --yes so the prompt can be answered

Example fix

// before
wmill workspace fork --yes   # fails on non-base branch
// after
wmill workspace fork --from-branch main

Defensive patterns

Strategy: validation

Validate before calling

const baseBranches = listConfiguredBaseBranches(config);
if (!baseBranches.includes(currentBranch) && !process.stdin.isTTY) {
  // add --from-branch <base> before invoking
}

Type guard

function isBaseBranch(branch: string, config: Config): boolean {
  return listConfiguredBaseBranches(config).includes(branch);
}

Try / catch

try {
  await createWorkspaceFork(opts, config, currentBranch);
} catch (e) {
  if (String(e.message).includes('not a base branch')) {
    await createWorkspaceFork({ ...opts, fromBranch: 'main' }, config, currentBranch);
  } else throw e;
}

Prevention

Always pass --from-branch when scripting fork creation
Check `git branch --show-current` against configured base branches before calling
Avoid --yes on non-base branches

When it happens

Trigger: Running `wmill workspace fork` (or `createWorkspaceFork` calling `resolveWorkingBranchBase`) while on a non-base branch, with `process.stdin.isTTY` false or `opts.yes === true`.

Common situations: CI/CD pipelines or scripts invoking `wmill workspace fork` while checked out on a feature branch; forgetting `--from-branch`; contributors branching off another feature branch instead of a base branch.

Related errors

AI-assisted analysis of windmill-labs/windmill@e474e8803c (2026-09-03). Data as JSON: /api/errors/ce22d0a1900a097c. Report an issue: GitHub.