Java library file C:\Users...\AppData\Local\Xamarin\Android.Support.v4\21.0.3\embedded\classes.jar doesn't exist.

Problem:

I installed the Xamarin Android Support Library v7 AppCompat nuget package into my project.  When I go to build it out I get prompted with the error:

C:\Program Files (x86)\MSBuild\Xamarin\Androi\Xamarin.Android.Common.targets(236,2): 

error XA5207: Please install package: 'Android Support Library' available in SDK installer. 

 Java library file C:\Users...\AppData\Local\Xamarin\Android.Support.v4\21.0.3\embedded\classes.jar doesn't exist.

Solution:

Delete folder: 21.0.3 (...\AppData\Local\Xamarin\Android.Support.v4\21.0.3)

Source:

http://stackoverflow.com/questions/28437601/error-after-updating-the-android-support-library-v7-appcompat-to-the-21-0-3-vers