Now I was wondering if anyone has been able to accomplish reverting to a previous ADT plugin. The reason for this is because I am using an open source jar and I am getting the following errors on my LogCat such as: unable to resolve virtual method unable to find class referenced in signature unable to resolve new-instance The effect of this causes an error on running my android application on the debugger. I was using android ADT 15 before now I am updated to 17. Please help on finding a solution to resolve the issue. Edit* Forgot to add in The error "java.lang.NoClassDefFoundError". In simple terms it can't find classes or methods the attached jar even though it allows it.