tailwindlabs/tailwindcss · error · Error

Invalid value for --format: ${input}

Error message

Invalid value for --format: ${input}

What it means

The `canonicalize` CLI subcommand accepts only three `--format` values: `text`, `json`, and `jsonl`. `parseFormat` does an exact-match comparison against these and throws for anything else, so a typo or an unsupported format fails fast with a descriptive message rather than producing malformed output.

Source

Thrown at packages/@tailwindcss-cli/src/commands/canonicalize/index.ts:289

  let content = await fs.readFile(resolvedCssFile, 'utf8')
  return __unstable__loadDesignSystem(content, {
    base: path.dirname(resolvedCssFile),
  })
}

function splitCandidateGroups(input: string) {
  return input
    .split(/\r?\n/g)
    .map((line) => line.trim())
    .filter((line) => line.length > 0)
}

function parseFormat(input: string): OutputFormat {
  if (input === 'text' || input === 'json' || input === 'jsonl') {
    return input
  }

  throw new Error(`Invalid value for --format: ${input}`)
}

function usageError(message: string): RunCommandLineResult {
  return {
    exitCode: 1,
    stdout: helpMessage() ?? '',
    stderr: message,
  }
}

function splitCandidates(input: string) {
  let trimmedInput = input.trim()
  if (trimmedInput.length === 0) return []

  return segment(trimmedInput, ' ')
    .map((candidate) => candidate.trim())
    .filter((candidate) => candidate.length > 0)
}

View on GitHub (pinned to 16e94cbf7f)

Solutions

1. Set `--format` to one of `text`, `json`, or `jsonl`.
2. If invoking `parseFormat` programmatically, validate the input against the set `['text','json','jsonl']` before calling, and route failures through `usageError` to print help on stderr.

Example fix

# before
tailwindcss canonicalize --format yaml

# after
tailwindcss canonicalize --format json

const FORMATS = new Set(['text', 'json', 'jsonl'])
function safeParseFormat(input: string): OutputFormat | never {
  if (!FORMATS.has(input)) {
    process.stderr.write(`Invalid --format: ${input}. Valid: ${[...FORMATS].join(', ')}\n`)
    process.exit(1)
  }
  return input as OutputFormat
}

function isOutputFormat(v: string): v is OutputFormat {
  return v === 'text' || v === 'json' || v === 'jsonl'
}

When it happens

Trigger: Running `tailwindcss canonicalize --format xml ...` (or yaml, csv, pretty, etc.). The argument fails all three equality checks in `parseFormat` and throws at index.ts:289. Note: the result is intended to be turned into a usage error by the caller (`usageError`), but the raw throw surfaces if `parseFormat` is called directly.

Common situations: Scripting around the canonicalize command with a guessed format name, or a CI flag value coming from an env var that is empty or misspelled.

AI-assisted analysis of tailwindlabs/tailwindcss@16e94cbf7f (2026-08-12). Data as JSON: /api/errors/acabcaa0c8093376. Report an issue: GitHub.