After updating my android SDK, getting an error for in-app purchases

I use the Soomla plugin, and I just updated the android SDK version 21 and had to change the target sdk version in my manifest file to 21 in order to build. Now The game will build and run, but I get an error when trying to do an in-app purchase.

Can you turn on the debug logs and post the logs with the errors?
Are you using Google Play or Amazon?
Can you post full reproduction steps?