Multiple dex files define Lcom/google/ads/AdRequest$ErrorCode and Multiple dex files define Lcom/google/ads/AdRequest$ErrorCode

google-pay-services.jar and GoogleAdMobAdsSdk.jar having same class name for AdMob. May be due to that reason you are getting multiple .dex files.

Please follow the docs steps of this sample code link of AdMob by using google-pay-services.jar instead of GoogleAdMobAdsSdk.jar.

Hope it will help you, Still you have any problem then let me know...

I had this error.

Make sure google-play-service.jar is not added twice (even in different modules...as in my case). It takes long time to debug those bugs.

Eclipse project properties->Java build path->Order and export

Un-check Android private libraries.