Windows 2003 server can currently only install the Dotnet Frameworks 4.0 framework and cannot install Dotnet frameworks 4.5 and 4.5.1 if you want to run 2003 assemblies on Razorengine server. Then you have to refer to the compilation target is version 4.0, while System.Web.Razor.dll this assembly is also NET4.0, if the compilation target is not 4.0 platform, then there will be a method in this assembly to refer to the 4.5 framework method, so is unable to run in Win2003 On the server system.
The way to solve the problem is to Recompile yourself System.Web.Razor.dll This assembly is a 4.0 target platform, and then recompile the RazorEngine.dll assembly, RazorEngine.dll the Assembly needs to re-reference the System.Web.Razor.dll of the 4.0 platform.
Fortunately I have downloaded Razorengine and System.Web.Razor source code, and fixed this problem, let Razorengine can run in Win2003 Server dotNET4.0 framework.
To download the source code of this solution, go here: https://github.com/sanxia/RazorEngineNET4.0.git
Let Windows2003 Server NET4.0 frameworks be able to use the Razorengine assembly.