denoland/deno · error · TypeError

Request mode 'navigate' is not allowed

Error message

Request mode 'navigate' is not allowed

What it means

Request constructor step 19 rejects init.mode === 'navigate' with TypeError 'Request mode 'navigate' is not allowed'. Navigate mode is reserved for browser document loads and cannot be created from script per the Fetch spec; all other mode values ('same-origin', 'cors', 'no-cors') pass through unvalidated here.

Source

Thrown at ext/fetch/23_request.js:450

          (parsedReferrer.protocol === "about:" &&
            parsedReferrer.pathname === "client")
        ) {
          request.referrer = "client";
        } else {
          request.referrer = parsedReferrer.href;
        }
      }
    }

    // 18. referrerPolicy
    if (init.referrerPolicy !== undefined) {
      request.referrerPolicy = init.referrerPolicy;
    }

    // 19. mode
    if (init.mode !== undefined) {
      if (init.mode === "navigate") {
        throw new TypeError("Request mode 'navigate' is not allowed");
      }
      request.mode = init.mode;
    }

    // 20. credentials
    if (init.credentials !== undefined) {
      request.credentialsMode = init.credentials;
    }

    // 21. cache
    if (init.cache !== undefined) {
      request.cacheMode = init.cache;
    }

    // If request's cache mode is "only-if-cached" and request's mode is not
    // "same-origin", then throw a TypeError.
    if (
      request.cacheMode === "only-if-cached" && request.mode !== "same-origin"

View on GitHub (pinned to 89f33cbef2)

Solutions

1. Remove the mode: 'navigate' option entirely (default mode is usually 'cors')
2. Use 'same-origin', 'cors', or 'no-cors' as appropriate
3. Strip unknown/unsupported keys in generic fetch wrappers before constructing Request

Example fix

// before
await fetch(url, { mode: 'navigate' });

// after
await fetch(url, { mode: 'cors' });

const MODES = new Set(['same-origin', 'cors', 'no-cors']);
function normalizeMode(mode) {
  if (mode == null) return undefined;
  const m = String(mode);
  if (!MODES.has(m)) throw new Error(`unsupported mode: ${m} (navigate is not allowed)`);
  return m;
}

/** @param {unknown} m */
function isAllowedRequestMode(m) {
  return m == null || ['same-origin', 'cors', 'no-cors'].includes(m);
}

When it happens

Trigger: new Request(url, { mode: 'navigate' }) or fetch(url, { mode: 'navigate' }).

Common situations: Porting browser code or specs that mention navigate mode, generic option-forwarding wrappers that copy a mode value from elsewhere, or confusion between request.mode and navigation concepts.

Related errors

• Method is forbidden
• Invalid header: length must be 2, but is ${header.length}
• Cannot read headers: request closed
• cannot read url: request closed
• Cannot read url: request closed

AI-assisted analysis of denoland/deno@89f33cbef2 (2026-08-16). Data as JSON: /api/errors/5e949eaa6a62edb1. Report an issue: GitHub.