vercel/next.js · error · Error

Invalid redirect arguments. Please use a single argument URL

Error message

Invalid redirect arguments. Please use a single argument URL, e.g. res.redirect('/destination') or use a status code and URL, e.g. res.redirect(307, '/destination').

What it means

Thrown by redirect() (wired to res.redirect in API routes) when the arguments do not match the two accepted signatures: a single string URL, or a numeric status code plus a string URL. This protects against ambiguous calls and ensures a valid HTTP redirect is emitted.

Source

Thrown at packages/next/src/server/api-utils/index.ts:68

}

/**
 *
 * @param res response object
 * @param [statusOrUrl] `HTTP` status code of redirect
 * @param url URL of redirect
 */
export function redirect(
  res: NextApiResponse,
  statusOrUrl: string | number,
  url?: string
): NextApiResponse<any> {
  if (typeof statusOrUrl === 'string') {
    url = statusOrUrl
    statusOrUrl = 307
  }
  if (typeof statusOrUrl !== 'number' || typeof url !== 'string') {
    throw new Error(
      `Invalid redirect arguments. Please use a single argument URL, e.g. res.redirect('/destination') or use a status code and URL, e.g. res.redirect(307, '/destination').`
    )
  }
  res.writeHead(statusOrUrl, { Location: url })
  res.write(url)
  res.end()
  return res
}

export function checkIsOnDemandRevalidate(
  rawHeaders: Headers | IncomingHttpHeaders,
  previewProps: __ApiPreviewProps
): {
  isOnDemandRevalidate: boolean
  revalidateOnlyGenerated: boolean
} {
  // Headers is a plain object for Node.js, Headers object in Edge runtime
  if (typeof rawHeaders.get === 'function') {

View on GitHub (pinned to 0ae8c72462)

Solutions

Use res.redirect('/destination') for a default 307 redirect.
Use res.redirect(307, '/destination') — number first, then string URL.
Ensure the status code is a number (not a string) and the URL is a string.

Example fix

// before
res.redirect('/dest', 307) // wrong order
res.redirect(307)        // missing url
// after
res.redirect('/dest')
res.redirect(307, '/dest')

Defensive patterns

Strategy: type-guard

Validate before calling

function safeRedirect(res: any, statusOrUrl: string | number, url?: string) {
  if (typeof statusOrUrl === 'string') { res.redirect(statusOrUrl); return }
  if (typeof statusOrUrl === 'number' && typeof url === 'string') { res.redirect(statusOrUrl, url); return }
  throw new Error('Invalid redirect arguments')
}

Type guard

function isValidRedirectArgs(statusOrUrl: unknown, url?: unknown): boolean {
  if (typeof statusOrUrl === 'string' && url === undefined) return true
  if (typeof statusOrUrl === 'number' && typeof url === 'string') return true
  return false
}

Prevention

Use res.redirect('/path') or res.redirect(307, '/path') — number first.
Do not pass two strings or reversed argument order.
Ensure status codes are numbers, not strings.

When it happens

Trigger: Calling res.redirect() with no arguments, with two strings, with a non-number/non-string mix, or with a status that isn't a number. The check at line 67 fails when statusOrUrl isn't a number or url isn't a string after the single-string normalization.

Common situations: Passing res.redirect(url, status) in the wrong order (a common mistake from Express differences); calling res.redirect(200); res.redirect(undefined); or res.redirect(status, url) where status came in as a string.

Related errors

AI-assisted analysis of vercel/next.js@0ae8c72462 (2026-08-06). Data as JSON: /api/errors/07bad45471ca93e6. Report an issue: GitHub.