Changing Firebase Package Name

As Eurosecom commented, you can just add a new Android app to your existing Firebase project with the new package name. After doing this, download the updated google-services.json and add it to your app.

Note that Firebase does not use the actual package name from your Java code, but uses the applicationId from your app's build.gradle file:

defaultConfig {
    applicationId "com.firebase.hearthchat"

When you initially create a project in Android Studio, the package name and application id will have the same value. But if you refactor your code into a different package, the application id won't be updated. That explains why the app will continue to work after such a refactoring. But it can be confusing at times, which is why I prefer keeping them in sync.

If you are using Firebase assistant then:

• Delete your app in the Firebase console in the project settings.
• Back in Firebase assistant reconnect to the Firebase for any service.
• It will ask you to sync with the project. Click on Sync.
• The app with new package will be added and the google-services.json file will be automatically updated.

Also note that the package name of the applicationId value in the build.gradle file is considered.

Cheers