asp.net-mvc-4 – 无法加载文件或程序集’System.Web.Http.WebHost,Version = 4.0.0.0,Culture = neutral,PublicKeyToken = 31bf3856ad364e35′

在Visual Studio 2012中，我创建了一个ASP.NET MVC 4项目，目标框架是.NET Framework 4.5。当我将项目部署到Web服务器时，会出现以下错误：

Could not load file or assembly 'System.Web.Http.WebHost,Version=4.0.0.0,Culture=neutral,PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file 
specified.

Description: An unhandled exception occurred during the execution of the current web request.
 Please review the stack trace for more information about the error and where
it originated in the code. 

Exception Details: System.IO.FileNotFoundException: Could not load file or 
assembly 'System.Web.Http.WebHost,PublicKeyToken=31bf3856ad364e35' or one of its dependencies.
 The system cannot find the file specified.

Source Error: 


Version information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34237

解决方法

检查已部署项目的bin文件夹。它应该包含System.Web.Http.WebHost.dll。 如果这个dll在这个文件夹，检查它的版本。如果不是4.0.0.0，那么你应该部署4.0.0.0版本或者更改你的web配置来使用其他版本(不是很好，因为依赖)