gildas-lormeau/SingleFile · error · Error

Cannot identify the extension requesting SingleFile capture

Error message

Cannot identify the extension requesting SingleFile capture

What it means

requestPermission in external-capture-permissions.js validates that the incoming message originates from a browser extension with a sender.id. If sender is missing or has no id, it throws this error because the caller's extension cannot be identified or checked against the allow/deny permission lists.

Source

Thrown at src/core/bg/external-capture-permissions.js:50

let requestId = 0;

export {
	onMessage,
	requestPermission
};

if (browser.tabs.onRemoved) {
	browser.tabs.onRemoved.addListener(tabId => {
		Array.from(pendingRequests.values())
			.filter(request => request.tabId == tabId)
			.forEach(request => resolveRequest(request, false));
	});
}

async function requestPermission(sender, message = {}) {
	const extensionId = sender && sender.id;
	if (!extensionId) {
		throw new Error("Cannot identify the extension requesting SingleFile capture");
	}
	const permissions = await config.getExternalCapturePermissions();
	if (permissions.allowedExtensionIds.includes(extensionId)) {
		return true;
	}
	if (permissions.deniedExtensionIds.includes(extensionId)) {
		return false;
	}
	const { request, created } = getOrCreatePendingRequest(extensionId, sender, message);
	if (created) {
		await openOptionsPage(request);
	}
	return request.promise;
}

async function onMessage(message, sender) {
	if (!isOptionsPageSender(sender)) {
		throw new Error("Unauthorized sender");

View on GitHub (pinned to 517fb7c5cf)

Solutions

1. Ensure the caller is a real extension and calls chrome.runtime.sendMessage(EXTENSION_ID, ...) so sender.id is populated
2. Update the integrating extension to the latest version that sends proper sender metadata
3. Verify the message route is onMessageExternal (external messages) not an internal handler
4. If you control the caller, pass a valid sender object when invoking requestPermission

Example fix

// before
chrome.runtime.sendMessage(msg); // from a page, no sender.id
// after
chrome.runtime.sendMessage(SINGLEFILE_EXTENSION_ID, msg); // sender.id set

// caller-side check before messaging SingleFile
chrome.runtime.sendMessage(SINGLEFILE_ID, { method: 'initiateCapture' }, response => {
  if (chrome.runtime.lastError) { /* handle: sender.id missing or not allowed */ }
});

function hasExtensionSender(sender) {
  return Boolean(sender && typeof sender.id === 'string' && sender.id.length > 0);
}

try {
  await requestPermission(sender, message);
} catch (error) {
  if (error.message.includes('Cannot identify the extension')) {
    // reject the request: caller is not an identifiable extension
  } else { throw error; }
}

When it happens

Trigger: An external runtime.onMessage / onMessageExternal event delivers a request to initiate a SingleFile capture where the `sender` object is absent or `sender.id` is undefined (e.g. message from a web page, service worker context without id, or malformed call).

Common situations: A web page or non-extension script messaging SingleFile directly; a third-party integration calling the external API incorrectly; browser (e.g. Safari/Firefox variant) delivering a sender shape without id; test harness invoking requestPermission without a sender.

Related errors

• Unauthorized sender
• Cannot access the tab contents
• URL is empty
• SingleFile capture was not approved for this extension
• SingleFile capture config must be an object

AI-assisted analysis of gildas-lormeau/SingleFile@517fb7c5cf (2026-09-01). Data as JSON: /api/errors/dbf719b2e2f56aa7. Report an issue: GitHub.