Firebase App named '[DEFAULT]' already exists (app/duplicate-app) [duplicate]

Answer 1

In my case, I was not explicitly calling initializeApp() more than once, so I was still confused after reading the main answers. Turns out that if you use Firebase hosting, then initialization is called automatically through SDK auto-configuration, i.e. when you have this line in index.html:<script src="/__/firebase/init.js"></script> you don't need to call initializeApp(config).

"When you deploy to Firebase or test your app locally, this script automatically configures the Firebase JavaScript SDK for the active Firebase project and initializes the SDK." SDK auto-configuration

Answer 2

i only glanced at your github repo to see that there is more .js files than suggested in your question. i had 2 separate .js files. both being included on the same html page that were both configuring and initializing the default app when it only needed to be done once for that page i believe. what worked for me was to comment out the second "initializeApp()" and i no longer got that error. try to look for the below in your .js and comment out or delete one of the initializations.

var config = { apiKey: "my api key", authDomain: "something.firebaseapp.com", databaseURL: "https://somesite.firebaseio.com", projectId: "myProjectId", storageBucket: "somesite.appspot.com", messagingSenderId: "someIntegers" }; //firebase.initializeApp(config);

Answer 3

I have had the same problem

if you are using ES6 modules and you installed firebase by npm you can not put init scrips into index.html

it is duplications of firebase dependancies