Oh how I have not missed you little error message: “The application requires that assembly Windowsbase Version 126.96.36.199 be installed in the Global Assembly Cache first.“
The first time I saw this I chuckled. I went and looked up to confirm my suspicions and then … verifying I was on Widows 2008R2, I proceeded to my Server Manager>Features and add “.NET Framework 3.5.1 Features” accept defaults (add required role services>next>next>next>install) reboot>patch>reboot and done. Your issue is resolved.
HOWEVER, if you have come here, and you find you have .NET 3.5.1 role already installed, go ahead and uninstall>reboot>follow the above … there now isn’t that better?