Login through Facebook using OAuth issue with Firebase (App_id in the input_token did not match the Viewing App)

Question

I am trying to login through Facebook, collect some data over OAuth and then login to Firebase using the credential. I am however encountering an issue (please see logs below).

CODE EXAMPLE

@objc func signInWFB() {

    let fbLoginManager : FBSDKLoginManager = FBSDKLoginManager()

    fbLoginManager.logIn(withReadPermissions: ["email","user_birthday","user_gender"], from: self) { (result, error) -> Void in

        if (error == nil) {
            let fbloginresult : FBSDKLoginManagerLoginResult = result!
            if (result?.isCancelled)! {
                print(result ?? FBSDKLoginManagerLoginResult())
            } else if(fbloginresult.grantedPermissions.contains("email")) {
                if((FBSDKAccessToken.current()) != nil) {
                    FBSDKGraphRequest(graphPath: "me", parameters: ["fields": "id, name, first_name, last_name, email, birthday, gender"]).start( completionHandler: { (connection, result, error) -> Void in
                        if (error == nil) {
                            //everything works print the user data
                            print(result ?? AnyObject.self)

                            if let d = result as? [String:Any] {

                                // ALL GOOD UP TO HERE

                                let credential = FacebookAuthProvider.credential(withAccessToken: FBSDKAccessToken.current()!.tokenString)

                                Auth.auth().signIn(with: credential) { (authResult, error) in
                                    if let error = error {
                                        print(error) // ERROR HERE
                                        return
                                    }

                                    // ...
                                }
                            }
                        }
                    })
                }
            }
        }
    }
}

LOGS

Error Domain=FIRAuthErrorDomain Code=17004 "Unsuccessful debug_token response from Facebook: {"error":{"message":"(#100) The App_id in the input_token did not match the Viewing App","type":"OAuthException","code":100,"fbtrace_id":"BwV3jZweRqo"}}" UserInfo={NSLocalizedDescription=Unsuccessful debug_token response from Facebook: {"error":{"message":"(#100) The App_id in the input_token did not match the Viewing App","type":"OAuthException","code":100,"fbtrace_id":"BwV3jZweRqo"}}, error_name=ERROR_INVALID_CREDENTIAL}

WHAT I'VE TRIED

1. Info plist has correct FacebookAppID and AccountKitClientToken
2. Tried both ON / OFF for "Require App Secret" in Facebook settings
3. OAuth redirect URI from Firebase added to Facebook settings

Answer 1

This was ridiculously hard to find. I had to go to Firebase > Authentication > Sign-in Method > Facebook and change the fields in there to match those on Facebook developer. For some inexplicable reason they were different...

Answer 2

If you're using expo with React Native, this might save you some time. Because at the moment, Facebook Login on iOS can only work with standalone apps.