Я получил эту ошибку при добавлении admob в проект.
полная ссылка на проект
Severity Code Description Project File Line Suppression State Suppression State
Error error: MediationRewardedVideoAdListenerImplementor is not abstract and does not override abstract method zzc(Bundle) in MediationRewardedVideoAdListener
public class MediationRewardedVideoAdListenerImplementor app\App8\obj\Debug\90\android\src\mono\com\google\android\gms\ads\reward\mediation\MediationRewardedVideoAdListenerImplementor.java 4