jestjs/jest · error · Error

The --ignoreProjects option requires the name of at least on

Error message

The --ignoreProjects option requires the name of at least one project to be specified.
Example usage: jest --ignoreProjects my-first-project my-second-project

What it means

Mirror of the selectProjects guard: `check` throws (packages/jest-cli/src/args.ts:70) when `--ignoreProjects` is given an empty array. ignoreProjects excludes projects by `displayName`, so at least one name must be supplied.

Source

Thrown at packages/jest-cli/src/args.ts:71

    argv.maxWorkers === undefined
  ) {
    throw new Error(
      'The --maxWorkers (-w) option requires a number or string to be specified.\n' +
        'Example usage: jest --maxWorkers 2\n' +
        'Example usage: jest --maxWorkers 50%\n' +
        'Or did you mean --watch?',
    );
  }

  if (argv.selectProjects && argv.selectProjects.length === 0) {
    throw new Error(
      'The --selectProjects option requires the name of at least one project to be specified.\n' +
        'Example usage: jest --selectProjects my-first-project my-second-project',
    );
  }

  if (argv.ignoreProjects && argv.ignoreProjects.length === 0) {
    throw new Error(
      'The --ignoreProjects option requires the name of at least one project to be specified.\n' +
        'Example usage: jest --ignoreProjects my-first-project my-second-project',
    );
  }

  if (
    argv.config &&
    !isJSONString(argv.config) &&
    !new RegExp(
      `\\.(${constants.JEST_CONFIG_EXT_ORDER.map(e => e.slice(1)).join('|')})$`,
      'i',
    ).test(argv.config)
  ) {
    throw new Error(
      `The --config option requires a JSON string literal, or a file path with one of these extensions: ${constants.JEST_CONFIG_EXT_ORDER.join(
        ', ',
      )}.\nExample usage: jest --config ./jest.config.js`,
    );

View on GitHub (pinned to f49721c78e)

Solutions

1. Pass the project display names to ignore: `jest --ignoreProjects e2e-heavy`.
2. Guard the call site when the list is dynamic: only add the flag when names exist.
3. Confirm each name matches a configured `displayName`.

Example fix

# before
jest --ignoreProjects

# after
jest --ignoreProjects slow-e2e integration

function requireIgnoreNames(names?: string[]): string[] {
  if (!names || names.length === 0) throw new Error('--ignoreProjects needs >=1 displayName');
  return names;
}

const hasIgnoreNames = (a: any) => Array.isArray(a.ignoreProjects) && a.ignoreProjects.length > 0;

When it happens

Trigger: `jest --ignoreProjects` with no names; dynamic name list that resolved to empty.

Common situations: Scripts that build an ignore list from a conditionally-empty variable; CI configs left with a placeholder.

Related errors

• The --selectProjects option requires the name of at least on
• Both --runInBand and --maxWorkers were specified, only one i
• Both --${key} and --watchAll were specified, but cannot be u
• Both --onlyFailures and --watchAll were specified, only one
• The --findRelatedTests option requires file paths to be spec

AI-assisted analysis of jestjs/jest@f49721c78e (2026-08-03). Data as JSON: /data/errors/48db43f87bcea5f1.json. Report an issue: GitHub.