MagicMirrorOrg/MagicMirror · error

${error.message}

Error message

${error.message}

What it means

The /cors route wraps all proxied work (header parsing, DNS pinning, fetch, response forwarding) in a try/catch. Any thrown error — including the internal `Response status: <code>` thrown for non-OK upstream responses and 'Invalid format for header ...' from malformed sendheaders — is surfaced as HTTP 500 with `{error: error.message}`. The server log records 'Error in CORS request: ...' (suppressed under mmTestMode=true).

Source

Thrown at js/server_functions.js:143

			});

			const response = await undici.fetch(url, { dispatcher, headers: headersToSend });
			if (response.ok) {
				for (const header of expectedReceivedHeaders) {
					const headerValue = response.headers.get(header);
					if (header) res.set(header, headerValue);
				}
				const arrayBuffer = await response.arrayBuffer();
				res.send(Buffer.from(arrayBuffer));
			} else {
				throw new Error(`Response status: ${response.status}`);
			}
		}
	} catch (error) {
		if (process.env.mmTestMode !== "true") {
			Log.error(`Error in CORS request: ${error}`);
		}
		res.status(500).json({ error: error.message });
	}
}

/**
 * Gets headers and values to attach to the web request.
 * @param {string} url - The url containing the headers and values to send.
 * @returns {object} An object specifying name and value of the headers.
 */
function getHeadersToSend (url) {
	const headersToSend = { "User-Agent": getUserAgent() };
	const headersToSendMatch = new RegExp("sendheaders=(.+?)(&|$)", "g").exec(url);
	if (headersToSendMatch) {
		const headers = headersToSendMatch[1].split(",");
		for (const header of headers) {
			const keyValue = header.split(":");
			if (keyValue.length !== 2) {
				throw new Error(`Invalid format for header ${header}`);
			}

View on GitHub (pinned to 4b4a59534f)

Solutions

1. Read the error.message in the 500 response body — for 'Response status: N', fix the upstream request (URL, auth headers) so the target returns 2xx
2. Check the MagicMirror server log ('Error in CORS request: ...') for the full stack — run without mmTestMode=true
3. Fix sendheaders format: comma-separated, each entry strictly 'name:value' with exactly one colon
4. If upstream requires auth, use **SECRET_*** placeholders with cors set to disabled/allowWhitelist (not allowAll) and ensure the env var is actually set
5. Verify the target URL is reachable from the server (curl it directly)

Example fix

// before
sendheaders=Authorization
// after
sendheaders=Authorization:Bearer%20<token>

// validate header params before building the request
const pairs = headerString.split(",");
if (pairs.some(p => p.split(":").length !== 2)) throw new Error("sendheaders entries must be name:value");
// optionally preflight upstream: curl -I <upstream-url>

function isCorsProxy500(body) {
  return typeof body === "object" && body !== null && typeof body.error === "string";
}

try {
  const r = await fetch(proxyUrl);
  if (!r.ok) {
    const { error } = await r.json();
    throw new Error(`CORS proxy: ${error}`); // e.g. 'Response status: 401'
  }
} catch (e) {
  Log.error(`Feed fetch failed: ${e.message}`);
  // retry later / show placeholder UI
}

When it happens

Trigger: Upstream fetch returns non-2xx (thrown as `Response status: 404/401/...`); malformed sendheaders/expectedheaders params (js/server_functions.js:160 rejects header strings without exactly one ':'); DNS failure or network error during undici.fetch; secret placeholder missing from process.env leaving an unparsable URL.

Common situations: Expired API key causing upstream 401/403; dead or renamed feed URL causing 404; sending sendheaders=a:b,c (missing colon); TLS/network errors to the upstream host; testing with mmTestMode so logs are hidden and only the 500 body remains.

Related errors

• Forbidden: domain not in corsDomainWhitelist
• ${this.logContext}${this.#shortenUrl()} - ${message} Retry #
• response.statusText

AI-assisted analysis of MagicMirrorOrg/MagicMirror@4b4a59534f (2026-08-31). Data as JSON: /api/errors/c639a64abda0d05c. Report an issue: GitHub.