Firebase: This domain is not authorized

Question

I imported Firebase JS v3 API and used to initialize Firebase using:

firebase.initializeApp(config);

However the app failed to load correct

Answer 1

Problem Authorised domain Firebase Locahost OAUTH2

If you are using Google Chrome you can see a problem with the Identity Toolkit API DISABLE. You need to enabled this API on the google cloud project to get OAUTH servcies in Firebase project.

https://console.developers.google.com/apis/api/identitytoolkit.googleapis.com/overview?project=project-id