NoClassDefFoundError: com.google.firebase.FirebaseOptions

Question

I keep on getting the NoClassDefFoundError on other test device (4.4.2) that I\'m using. But works fine on my test device (Android 5.1).

I tried the solutio

Answer 1

Thanks to TapanHP above I got this working quickly for me:

Short Answer:

I had multiDexEnabled= true set in my app/build.gradle file and this ran fine on Android 5.x.x above but any test device with 4.x.x (kit kat) would throw a critical error "Unfortunately, YourAppName has stopped."

Debugger showed:

Could not find class 'com.google.firebase.FirebaseOptions' ....

Note: I also have a custom class that extends Application.

My Solution: Added the following code to my custom Application class

import android.support.multidex.MultiDex;
public class YourCustomApplication extends Application {

    @Override
    protected void attachBaseContext(Context base) {
        super.attachBaseContext(base);
        MultiDex.install(this);
    }

...
} 

No more critical crash.