In this article, we’re going to learn how to easily fix the “auth/unauthorized domain” error which happens in the Firebase Authentication Web SDK.
What causes “auth/unauthorized domain” error in Firebase?
The Firebase “domain is not authorized” error happens when you try to use an API from Firebase Auth in a domain that is not authorized by Firebase.
It may occur in the FirebaseUI, or in your browser console.

How to fix “auth/unauthorized domain” error in Firebase
To fix the “Domain not authorized” error in Firebase Auth, go to the Firebase Authentication Authorized domains settings for your project, using this link: https://console.firebase.google.com/project/_/authentication/settings.
Or by following these steps from the Firebase Console for your project in this image:

Enter the new domain in the dialog that shows after clicking Add domain
:
