I am using 5.2.1p1 (64 bit) and I tried to build a Windows 10 Universal Project. The following line of code causes an error: XmlDocument mResourceDictionary; string result = mResourceDictionary.SelectSingleNode("//Resources/String[@ID='" + ID + "']").InnerText; The error states 'System.Xml.XmlDocument' contains no definition for 'SelectNodes' and no extension method 'SelectNodes' could be found. This also happened when building an Universal App for 8.1. This also happened when trying to use SelectSingleNode. The code compiles fine in VS 2015 and building standalone (for Windows) and Android worked!