denoland/deno · error · RangeError

The status provided (${init.status}) is not equal to 101 and

Error message

The status provided (${init.status}) is not equal to 101 and outside the range [200, 599]

What it means

initializeAResponse enforces the spec rule that a Response status is either 101 or within [200, 599]; anything else throws RangeError naming the offending value. This runs for new Response(...), Response.json(), and Response.redirect()-family constructors, before any body handling.

Source

Thrown at ext/fetch/23_response.js:518

  return resp;
}

/**
 * https://fetch.spec.whatwg.org#initialize-a-response
 * @param {Response} response
 * @param {ResponseInit} init
 * @param {{ body: fetchBody.InnerBody, contentType: string | null } | null} bodyWithType
 */
function initializeAResponse(
  response,
  init,
  bodyWithType,
  prefix,
  context,
) {
  // 1.
  if ((init.status < 200 || init.status > 599) && init.status != 101) {
    throw new RangeError(
      `The status provided (${init.status}) is not equal to 101 and outside the range [200, 599]`,
    );
  }

  // 2.
  if (
    init.statusText &&
    RegExpPrototypeExec(REASON_PHRASE_RE, init.statusText) === null
  ) {
    throw new TypeError(
      `Invalid status text: "${init.statusText}"`,
    );
  }

  // 3.
  response[_response].status = init.status;

  // 4.

View on GitHub (pinned to 89f33cbef2)

Solutions

1. Clamp or validate: use a status in 200-599 (or exactly 101) — for errors use 500
2. Check Number.isInteger(status) && ((status >= 200 && status <= 599) || status === 101) before constructing
3. Map custom application codes into the body/headers, not the HTTP status field

Example fix

// before
return new Response(body, { status: upstreamCode + 1 }); // could be 600

// after
const status = upstreamCode >= 200 && upstreamCode <= 599 ? upstreamCode : 502;
return new Response(body, { status });

function sanitizeStatus(status, fallback = 500) {
  const n = Number(status);
  return Number.isInteger(n) && ((n >= 200 && n <= 599) || n === 101) ? n : fallback;
}

/** @param {unknown} s */
function isValidResponseStatus(s) {
  const n = Number(s);
  return Number.isInteger(n) && ((n >= 200 && n <= 599) || n === 101);
}

When it happens

Trigger: new Response(body, { status: 199 }), { status: 600 }, { status: 102 }, or a status computed from arithmetic that lands outside the range (e.g. statusCode + 1).

Common situations: Forwarding upstream status codes that were transformed incorrectly, off-by-one math on status codes, mapping internal error codes (e.g. 1200, 7000) directly into Response statuses.

Related errors

• Invalid status text: "${init.statusText}"
• Response with null body status cannot have body
• Invalid redirect status code: ${status}
• Invalid header: length must be 2, but is ${header.length}
• Invalid header name: "${name}"

AI-assisted analysis of denoland/deno@89f33cbef2 (2026-08-16). Data as JSON: /api/errors/e5433285c32de043. Report an issue: GitHub.