No static method zzb?

I recently tried integrating both Firebase Remote Config and Google Mobile Ads into my project.

With just Firebase Remote Config, the build works fine. But once I integrated Google Mobile Ads, the build crashes on startup with the following error: http://pastebin.com/5GYMdrbd

" java.lang.NoSuchMethodError: No static method zzb(Ljava/lang/Object;Ljava/lang/ObjectLjava/lang/Object; in class Lcom/google/android/gms/common/internal/zzaa; or its super classes "

How do I fix this error? Could it be because Google Mobile Ads and Remote Config uses conflicting versions of Google Play Services?

Specs:
Unity 5.3.5f

 

The error occurs due to a missing method (Java) that is called, but cannot be found.

The method names (zzb / zzaa) look like obfuscated code. It may be, that Google mobile ads includes some libraries that are "colliding" with Firebase remote config, causing this error.

Could you list what other native plugins are you using ? from the crash, it looks like you are using something called Xposed?

Also, can you mention what plugins are you using for integrating Firebase and Google mobile ads?