today I just imported a sample app from Android SDK as a module in my project (analytics) and suddenly I got this gradle error when I try to sync it: Plugin is too old
In the past months, I used a "preview" version of Android Studio. I tried to switch back to the "stable" releases for the software updates but it wasn't enough and I got this famous error you talk of.
Uninstalling my Android Studio 2.2.preview and installing latest stable Android Studio (2.1) fixed it for me :)