Subtitle

How to set up Meta for Developers, Business ownership, Firebase Authentication, and native mobile config without mixing up App Domains, key hashes, and redirect URIs

Introduction

Facebook Login looks simple from the Flutter side. In code, it can be as small as calling FacebookAuth.instance.login() , converting the token to a Firebase credential, and signing the user in.

The real complexity is not in the Dart code. It is in the configuration spread across four systems:

Meta for Developers

Meta Business ownership and app access

Firebase Authentication

Native Android and iOS app configuration

If one of those layers is misconfigured, the failure usually shows up as a vague login cancellation, invalid OAuth redirect, key-hash error, or a token exchange failure. That is why treating Facebook Login as a console-configuration workflow, not only a code task, saves time.

This guide explains the full setup path using abstract examples instead of production identifiers.

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