affaan-m/ECC · error · Error

Invalid format: . Use text or json.

Error message

Invalid format: ${parsed.format}. Use text or json.

What it means

After parsing, parseArgs validates that the --format value is one of the two supported output formats, text or json. Any other value throws this error before any report generation runs. This is a whitelist check preventing downstream rendering from encountering unknown formats.

Solutions

1. Use --format text or --format json exactly (lowercase).
2. Fix casing, e.g. --format JSON -> --format json.
3. Fix typos in the format value.
4. If another format is genuinely needed, extend the whitelist array in parseArgs and the corresponding renderer.

Example fix

// before
node scripts/observability-readiness.js --format yaml
// after
node scripts/observability-readiness.js --format json

const i = args.indexOf('--format');
const fmt = i !== -1 ? args[i+1] : 'text';
if (!['text','json'].includes(fmt)) throw new Error(`--format must be 'text' or 'json', got: ${fmt}`);

const isReportFormat = (v) => v === 'text' || v === 'json';

try {
  runObservability(argv);
} catch (err) {
  if (err.message.startsWith('Invalid format:')) {
    console.error("Use --format text or --format json (lowercase).");
  } else throw err;
}

When it happens

Trigger: Running with `--format yaml`, `--format table`, or any misspelled value like `--format Json` (case-sensitive check); also --format followed by an unexpected token that slipped through readValue.

Common situations: Assuming more formats are supported (csv, markdown); shell casing differences like JSON vs json; an env-interpolated FORMAT variable holding an unsupported default.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• --host-provider must be anthropic, openai, or unknown
• Invalid --action value
• Invalid
• Invalid format: . Use text, json, or markdown.
• Invalid format: . Use text, json, or markdown.

AI-assisted analysis of affaan-m/ECC@8321021c54 (2026-09-16). Data as JSON: /api/errors/08b5d8f2e0edaf4d. Report an issue: GitHub.

Appendix: source

Thrown at scripts/observability-readiness.js:72

      continue;
    }

    if (arg === '--root') {
      parsed.root = path.resolve(readValue(args, index, arg));
      index += 1;
      continue;
    }

    if (arg.startsWith('--root=')) {
      parsed.root = path.resolve(arg.slice('--root='.length));
      continue;
    }

    throw new Error(`Unknown argument: ${arg}`);
  }

  if (!['text', 'json'].includes(parsed.format)) {
    throw new Error(`Invalid format: ${parsed.format}. Use text or json.`);
  }

  return parsed;
}

function fileExists(rootDir, relativePath) {
  return fs.existsSync(path.join(rootDir, relativePath));
}

function readText(rootDir, relativePath) {
  try {
    return fs.readFileSync(path.join(rootDir, relativePath), 'utf8');
  } catch (_error) {
    return '';
  }
}

function safeParseJson(text) {

View on GitHub (pinned to 8321021c54)