Android build fail. Execution failed for task Multiple dex files

I am trying to build my android app. I get the following error:

* What went wrong:

Execution failed for task ':transformClassesWithDexForDebug'.

ProcessException: java.util.concurrent.ExecutionException: 
Multiple dex files define Landroid/support/v4/app/NavUtils$NavUtilsImpl;

Can anyone help?

I found the issue to be the document viewer plugin I removed this and the support-v4.jar which this plugin depended on and is now fixed.