I have Android Studio Beta. I created a new project with compile my old modules but when I tried launching the app it did not launch with the message:
Error:
In my case it was gson-2.8.1.jar which I have added to libs folder of the project. But the reference was already there by SDK. So it was not necesary to add gson-2.8.1.jar to libs folder.
When I took it out th gson-2.8.1.jar project compiles without this wiered error.
So try to revise libs folder and dependencies.