I set up Firebase Crashlytics according to [Get started with Firebase Crashlytics](https://firebase.google.com/docs/crashlytics/get-started) for my Android app (using Android studio 3.1.3). On my own device as well as on the Emulator, everything works fine and my crashes appear correctly within the Firebase Console. So far so good.

However, there was a crash for one of my app users that was unexpected:

> 
> java.lang.IllegalStateException: Must Initialize Fabric before using singleton()
> 
> 
> 

The exception was thrown in another Activity than the MainActivity.

I am aware that you could manually execute the initialization as described [here](https://stackoverflow.com/questions/26535438/how-to-initialize-crashlytics-in-fabric-io) by calling `Fabric.with(this, new Crashlytics());` However, there is nothing said about one has to manually initialize the Crashlytics in the Getting Started article mentioned above. I was expecting this is done automatically since all my own tests run fine. So why is it that for some users Crashlytics is set up correctly and for some not?