title: Migrating my MVC 3 application to MVC 4
body: <p>I really do not know what to do, I'm following <a href="http://www.asp.net/learn/whitepapers/mvc4-release-notes" rel="noreferrer">this article</a> that shows how to migrate my MVC 3 application manually . </p>
  
  <p>I followed <strong>all the steps</strong> but when running my application the following error occurs:</p>
  
  <blockquote>
    <p>Server Error in '/' Application.</p>
    
    <p>Could not load file or assembly 'System.Web.WebPages.Razor,
    Version=1.0.0.0, 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)</p>
    
    <p>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. </p>
    
    <p>Exception Details: System.IO.FileLoadException: Could not load file or
    assembly 'System.Web.WebPages.Razor, Version=1.0.0.0, 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)</p>
    
    <p>Source Error: </p>
    
    <p>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.</p>
    
    <p>Assembly Load Trace: The following information can be helpful to
    determine why the assembly 'System.Web.WebPages.Razor,
    Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'
    could not be loaded.</p>
    
    <p>WRN: Assembly binding logging is turned OFF. To enable assembly bind
    failure logging, set the registry value
    [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There
    is some performance penalty associated with assembly bind failure
    logging. To turn this feature off, remove the registry value
    [HKLM\Software\Microsoft\Fusion!EnableLog].</p>
    
    <p>Stack Trace: </p>
    
    <p>[FileLoadException: Could not load file or assembly
    'System.Web.WebPages.Razor, Version=1.0.0.0, 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)]<br>
    Microsoft.Web.Samples.PreApplicationStartCode.Start() +0</p>
    
    <p>[InvalidOperationException: The pre-application start initialization
    method Start on type Microsoft.Web.Samples.PreApplicationStartCode
    threw an exception with the following error message: Could not load
    file or assembly 'System.Web.WebPages.Razor, Version=1.0.0.0,
    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).]<br>
    System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1
    methods) +423<br>
    System.Web.Compilation.BuildManager.CallPreStartInitMethods() +306<br>
    System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager
    appManager, IApplicationHost appHost, IConfigMapPathFactory
    configMapPathFactory, HostingEnvironmentParameters hostingParameters,
    PolicyLevel policyLevel, Exception appDomainCreationException) +677</p>
    
    <p>[HttpException (0x80004005): The pre-application start initialization
    method Start on type Microsoft.Web.Samples.PreApplicationStartCode
    threw an exception with the following error message: Could not load
    file or assembly 'System.Web.WebPages.Razor, Version=1.0.0.0,
    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).]<br>
    System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9079340 
    System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +97
    System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest
    wr, HttpContext context) +256</p>
    
    <p>Version Information: Microsoft .NET Framework Version:4.0.30319;
    ASP.NET Version:4.0.30319.237</p>
  </blockquote>
  
  <p><strong>I looked through the code, but I see no reference to System.Web.WebPages.Razor in version 1.0 version 2.0 only.</strong></p>