The type or namespace name 'Caching' does not exist in the namespace 'System.Runtime'
问题 I know there is usually a simple solution to this which is reference the dll in add references. But I have added the reference and system.runtime.caching appears in my references list but the error still displays. The error displays in the browser in runtime so it does compile. I have removed and re added the reference but still no luck. I have restarted VS 2012 and restarted. Visual Studio 2012 .net framework 4.5 Screen shot: 回答1: I had the same issue, and I found out that I manually had to