React-Native: Firebase Error: No Firebase App [DEFAULT] has been created - call Firebase App.initializeApp() (app/no-app) [duplicate]

Question

I am getting this error when I was trying to connect firebase with my React Native App.

Firebase Error: No Firebase App [DEFAULT] has been created - call Firebase App.initializeApp() (app/no-app)

I have added my code here-

    import { initializeApp } from "firebase/app";
    import { getAuth } from "firebase/auth";
    import { getFirestore } from "firebase/firestore";

   // Your web app's Firebase configuration
const RNfirebaseConfig = {
  apiKey: "........",
  authDomain: "note-app-rn.firebaseapp.com",
  projectId: "note-app-rn",
  storageBucket: "note-app-rn.appspot.com",
  messagingSenderId: ".....",
  appId: "......"
};

const app = initializeApp(RNfirebaseConfig);
export const auth = getAuth(app);
export const db = getFirestore(app);

Answer 1

Did it happen during migration to new React Native architecture?

Remember to change your import:

• from: @import Firebase; in AppDelegate.m
• to: #import <Firebase.h> in AppDelegate.mm

Answer 2

try this,

import firebase from '@react-native-firebase/app';
import '@react-native-firebase/auth';
import '@react-native-firebase/firestore';

const RNfirebaseConfig = {
  apiKey: "........",
  authDomain: "note-app-rn.firebaseapp.com",
  projectId: "note-app-rn",
  storageBucket: "note-app-rn.appspot.com",
  messagingSenderId: ".....",
  appId: "......"
};

let app;
if (firebase.apps.length === 0) {
    app = firebase.initializeApp(RNfirebaseConfig )
} else {
    app = firebase.app()
}

const db = firebase.firestore();
const auth = firebase.auth();