How to fix error - Could not load file or assembly 'DocumentFormat.OpenXml' or one of its dependencies.

Error Message:
Could not load file or assembly 'DocumentFormat.OpenXml' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded.






In my case I installed OpenXml version 2.5 on Visual Studio 2008.  To fix it:
install older version that supports .net3.5 (or upgrade visual studio to newer version :)