Could not load file or assembly 'System.Web.Http.WebHost, Version=4.0.0.0, Culture=neutral,PublicKeyToken=31bf3856ad364e35'

Question

In Visual Studio 2012 I created an ASP.NET MVC 4 project where the target framework is the .NET Framework 4.5. When I deployed my project to a web server it gave the followi

Answer 1

Important: This error message can be caused because you are deploying a 4.5 project to a server that doesn't have 4.0 installed. Make sure you have the .NET Framework version installed in IIS for the project you need. Some of these DLLs by default won't copy up, because it uses the core project DLL normally. Check to make sure your production server has the .NET version you're going with. I experienced this myself with a 4.5 project on a 4.0 server.

Answer 2

I had this error with an old project that I was going back to do a bit of work on. It turns out the project wasn't actually using WebApi so I uninstalled Microsoft.AspNet.WebApi using NuGet. That solved the problem for me.

If I'd actually have needed WebApi I'm sure installing it again would have fixed the error too.