Why Firebase Auth works but Firestore fails in React Native

If Firebase Auth works in a React Native app, it is very tempting to assume the rest of Firebase is configured correctly too. But that is not always true. One of the more frustrating debugging patterns is this: sign-in works the user exists auth state looks valid but Firestore requests still fail Sometimes the error is permission-denied . Sometimes it looks like missing data. Sometimes it only fails in release. And sometimes the real problem has very little to do with Auth itself. I ran into this kind of issue while debugging React Native Android + Firebase setups, and one of the most useful mindset shifts was this: If Auth works but Firestore fails, stop thinking in terms of “Firebase works” vs “Firebase does not work.” Start separating the layers. Auth working does not prove Firestore is fine Firebase Auth and Firestore are related, but they do not prove each other. Auth working only proves certain things, such as: the app can talk to Firebase Auth sign-in flow is functioning the cur