Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0

Question

I just upgraded packages in an MVC 3 project (ASP.net 4), and now I am getting the following error message when accessing a page in that project:

Server Error in '/MyApplication' Application.

Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) 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.FileLoadException: Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Assembly Load Trace: The following information can be helpful to determine why the assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' could not be loaded.

=== Pre-bind state information === LOG: User = IIS APPPOOL\ASP.NET v4.0 LOG: DisplayName = System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 (Fully-specified) LOG: Appbase = file:///C:/.../ LOG: Initial PrivatePath = C:...\bin Calling assembly : Microsoft.Web.Helpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35. === LOG: This bind starts in default load context. LOG: Using application configuration file: C:...\web.config LOG: Using host configuration file: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet.config LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework64\v4.0.30319\config\machine.config. LOG: Post-policy reference: System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/.../cb62a7b2/327a0353/System.Web.WebPages.Razor.DLL. LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/.../cb62a7b2/327a0353/System.Web.WebPages.Razor/System.Web.WebPages.Razor.DLL. LOG: Attempting download of new URL file:///C:/LeGroupeHtmSVN/.../UpDir.Web/bin/System.Web.WebPages.Razor.DLL. WRN: Comparing the assembly name resulted in the mismatch: Major Version ERR: Failed to complete setup of assembly (hr = 0x80131040). Probing terminated.

Stack Trace:

[FileLoadException: Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)]
Microsoft.Web.Helpers.PreApplicationStartCode.Start() +0

[InvalidOperationException: The pre-application start initialization method Start on type Microsoft.Web.Helpers.PreApplicationStartCode threw an exception with the following error message: Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040).]
System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1 methods) +11711966
System.Web.Compilation.BuildManager.CallPreStartInitMethods() +465
System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +1167

[HttpException (0x80004005): The pre-application start initialization method Start on type Microsoft.Web.Helpers.PreApplicationStartCode threw an exception with the following error message: Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040).]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11700896 System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141 System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4869125

-------------------------------------------------------------------------------- Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272

In my web.config file, and in my application, I am referencing System.Web.WebPages.Razor v1.0.0.0:

  <dependentAssembly>     <assemblyIdentity name="System.Web.WebPages.Razor" publicKeyToken="31bf3856ad364e35" culture="neutral" />     <bindingRedirect oldVersion="0.0.0.0-1.0.0.0" newVersion="1.0.0.0" />   </dependentAssembly> 

I don't even know whether I could be using System.Web.WebPages.Razor v2.0.0.0 with .Net 4.

Now, how do I find out what is referencing System.Web.WebPages.Razor v2.0.0.0?

Answer 1

So simple. In Nuget Package Manager Console:

Update-Package Microsoft.AspNet.Mvc -Reinstall

Answer 2

This problem started when I did 'Remove Unused References'. The website still worked on my local machine, but did not worked on the server after publishing.

I fixed this problem by doing the following,

1. Open 'Package Manager Console' in Visual Studio
2. Uninstall-Package Microsoft.AspNet.Mvc
3. Install-Package Microsoft.AspNet.Mvc