Error message about existing

I'm using VS 2010 with ASP.net MVC 2.

I recieved a program that was completed and when I was debugging the program I recieve an error message.

"Error 4 The type 'System.Web.Routing.RouteTable' exists in both 'C:\Program Files\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Web.dll' and 'C:\Documents and Settings\Vincent\Desktop\3\Manning.ASP.NET.MVC.2.in.Action.Jun.2010\aspnetmvc2inaction_code\lib\AspNetMvc\System.Web.Routing.dll' C:开发者_Go百科\Documents and Settings\Vincent\Desktop\3\Manning.ASP.NET.MVC.2.in.Action.Jun.2010\aspnetmvc2inaction_code\src\Chapter01\GuestBook\Global.asax.cs"

and

"Error 1 The type 'System.Web.Routing.RequestContext' exists in both 'c:\Program Files\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Web.dll' and 'c:\Documents and Settings\Vincent\Desktop\3\Manning.ASP.NET.MVC.2.in.Action.Jun.2010\aspnetmvc2inaction_code\lib\AspNetMvc\System.Web.Routing.dll' C:\Documents and Settings\Vincent\Desktop\3\Manning.ASP.NET.MVC.2.in.Action.Jun.2010\aspnetmvc2inaction_code\src\Chapter01\GuestBook\Controllers\AccountController.cs".

The program was converted into VS 2010 format.

What should I do?

// Fullmetalboy

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When you convert a project from .Net 2.0/3.5 to 4.0 in VS2010 the web projects will prompt you to upgrade the framework to 4.0 but you will need to manually go into the project properties and upgrade class library projects and certain other projects manually in the project properties. So this type of error is probably caused by your web project referencing the 4.0 version of System.Web.Routing but a class library in your solution is still referencing the 3.5 version.

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One of the projects in your solution is referencing a single type (RouteTable/RequestContext) in two different places. I always start with cleaning and rebuilding the solution, but if that doesn't fix it, you're going to have to check the project references and resolve it that way. If all else fails, try to make a new project from scratch and manually add the references and projects you need and then copy and paste your old code.

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Someone copied the ASP.NET MVC source code into the "lib" folder of your application and either included that folder in the project (so it is getting built when you build your project) or he/she built it before you got it and referenced it from within the project. Now it is in conflict with the ASP.NET libraries that exist in default installation folder on the system 'c:\Program Files\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Web.dll'.

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Since you're using the .NET 4.0 Framework, the library System.Web.Routing is ambiguous. Make sure you have referenced System.Web.dll (version 4.0) and remove the reference to System.Web.Routing.dll