n8n-io/n8n · error · Error

Unknown flag: ${arg.split('=', 1)[0]} (use --help)

Error message

Unknown flag: ${arg.split('=', 1)[0]} (use --help)

What it means

The langtracer-push CLI has a fixed set of recognized flags parsed in a switch statement. Any argument starting with '--' that does not match a known case falls through to the default branch, which throws this error naming the unrecognized flag and directing to --help. This prevents silent ignoring of typos that would change push behavior.

Source

Thrown at packages/@n8n/instance-ai/evaluations/cli/langtracer-push.ts:111

				}
				result.setKind = value;
				i += 2;
				break;
			}
			case '--contains-user-data':
				result.synthetic = false;
				i += 1;
				break;
			case '--dry-run':
				result.dryRun = true;
				i += 1;
				break;
			case '-h':
			case '--help':
				return { helpRequested: true };
			default:
				if (arg.startsWith('--')) {
					throw new Error(`Unknown flag: ${arg.split('=', 1)[0]} (use --help)`);
				}
				result.slugs.push(arg);
				i += 1;
				break;
		}
	}

	if (!result.suite) throw new Error('--suite <slug|id> is required');
	const hasSelector =
		result.slugs.length > 0 ||
		result.changed ||
		result.filter !== undefined ||
		result.tier !== undefined;
	if (!hasSelector) {
		throw new Error('select cases to push: pass <slugs...>, --changed, --filter, or --tier');
	}

	return { helpRequested: false, args: result };

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Run with --help to see all supported flags and their exact spelling
2. Check the flag name against the help text and correct the typo
3. Remove the unsupported flag if it was accidental

Example fix

# before
pnpm eval:langtracer-push --suite baseline --changed --dry-runn

# after
pnpm eval:langtracer-push --suite baseline --changed --dry-run

const KNOWN_FLAGS = new Set(['--suite', '--filter', '--exclude', '--tier', '--changed', '--set-kind', '--contains-user-data', '--dry-run', '-h', '--help']);
for (const arg of argv) {
  if (arg.startsWith('--') && !KNOWN_FLAGS.has(arg.split('=')[0])) {
    throw new Error(`Unknown flag: ${arg.split('=')[0]}. Run with --help for valid flags.`);
  }
}

When it happens

Trigger: Running `pnpm eval:langtracer-push --suite baseline --changed --dry-runn` (typo for --dry-run), or any unrecognized flag starting with '--'. The check at line 110 fires in the default case of the switch.

Common situations: Typo in a flag name. Using a flag from a different CLI (e.g. build-mcp-manifest's --source or --iterations). Version mismatch where a flag was added or removed. Copy-pasting a command from outdated documentation.

Related errors

• --set-kind must be "regression" or "capability_gap"
• --suite <slug|id> is required
• select cases to push: pass <slugs...>, --changed, --filter,
• Missing value for ${flag}
• --max-attempts must be >= 1

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/1e3a959d78e84184. Report an issue: GitHub.