Firebase: Error (auth/unauthorized-domain)
Your page’s host isn’t in Firebase’s Authorised domains list, so Firebase refuses to start sign-in. We re-checked this in our lab on 24 Oct 2026 on an unregistered host.
Fix (a console step you do yourself): Firebase console → Authentication → Settings → Authorised domains → add the exact host (console path as of Oct 2026). Every new domain or preview address needs its own entry.
The free check reads only your public page, never your Firebase settings, so this error is the signal to look for.
FAQ
What if it doesn’t work for me?
On Cloudflare Workers, it works or you get your money back within 14 days. Our refund policy says: “Works or your money back. If within 14 days you've followed the pack and Google's sign-in still doesn't show your domain, email support with your re-check link. We'll help you fix it, and if we can't, we refund you in full.” It covers apps served by Cloudflare Workers, the hosting setup we’ve tested, and sits alongside your rights under UK consumer law. Full terms: https://pewterkit.com/refunds
Do I need to be a developer?
Your fix pack has a paste-ready prompt for your AI builder, the exact snippet we tested, and a re-check that runs the free check on your app again, so you can see the name Google’s sign-in shows after your change.
Is the check safe?
It’s read-only. It reads your public page and its same-origin scripts, the same page any visitor can open, and sends no cookies. It never asks for a sign-in, a password or access to your accounts.
Which hosts does it cover?
Cloudflare Workers on your own domain. In our lab on Cloudflare Workers, Google’s sign-in showed our own domain (re-checked 24 Oct 2026). A workers.dev address can’t show your own domain at sign-in. You need a domain you own. On Cloudflare Pages, Firebase Hosting, Vercel or Netlify, run the free check, pick your host and leave your email: we’ll email you once when yours is ready.
What’s in the fix pack?
It’s built from the check we ran on the domain you entered: the exact snippet we tested for your host, the two console settings to change with the click path to each, a paste-ready prompt for your AI builder, and a re-check. One-time payment, no subscription.