Proguard Can't Find Referenced Class Com.google.ads.internal.state.adstate

Ok guys so this becoming extremely annoying trying to get my project to work when exporting/ Progaurd keeps giving me this error: Proguard returned with error code 1. See console

Solution 1:

This problem started with AdMob SDK 6.1.0 and 6.2.1 (for Android). To fix the error, add this to your proguard.cfg file:

-dontwarn com.google.ads.**

Source: https://groups.google.com/d/msg/google-admob-ads-sdk/JllLSIXWtBk/ioXzTWKoYgMJ