title: System.web.mvc missing
body: <p>We have an old ASP.NET MVC 3 Web Application, building in VS2010, that fails to compile, since last week's security update.</p>
  
  <p>The problem is that the reference to System.Web.Mvc.dll is broken. </p>
  
  <p>When I open the solution file on our build machine, where the security update has not run, and open the properties dialog for References->System.Web.MVC, it looks just fine. </p>
  
  <p>Path is C:\Program Files\Microsoft ASP.NET\ASP.NET MVC 3\Assemblies\System.Web.Mvc.dll
  Version is 3.0.0.0</p>
  
  <p>But when I open the solution file on a dev machine where the security update has run, References->System.Web.MVC is flagged as missing. If I remove it, and try to add it back using VS2010's Add Reference dialog, it doesn't show.</p>
  
  <p>Wandering around the web has led me to suggestions involving updating MVC using NuGet. We didn't use NuGet, in our VS2010 projects, so that doesn't seem quite right, for this situation. I tried it anyway, and ended up with half-a-dozen missing references.</p>
  
  <p>When I look at the properties for "C:\Program Files\Microsoft ASP.NET\ASP.NET MVC 3\Assemblies\System.Web.Mvc.dll" in Windows Explorer, on the build machine I see version 3.0.0.0.</p>
  
  <p>When I look at the properties on the dev machine, I see version 3.0.50813.1.</p>
  
  <p>What I need is a way to change the way I build and run so that I can build and run regardless of which of these two DLLs in installed in the .NET 3.0 framework.</p>
  
  <p>Ideas?</p>
  
  <h2>What I have tried that didn't work</h2>
  
  <p>First attempt - if the assembly is missing, add it.  I deleted the old missing reference. Then I copied the DLL from the "ASP.NET MVC3\Assemblies" folder, into a folder in my project. Set it as "Copy Always", and added it as a reference.</p>
  
  <p>With that, the project would compile in VS2010, but when I'd try to precompile the pages with aspnet_compiler, I got warnings:</p>
  
  <pre><code>(0): warning CS1702: Assuming assembly reference 'System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' matches 'System.Web.Mvc, Version=3.0.0.1, Culture=neutral, PublicKeyToken=31bf3856ad364e35', you may need to supply runtime policy
  </code></pre>
  
  <p>So far, I've been able to manage to avoid understanding runtime policies, but I tried to add this, in the web.config:</p>
  
  <pre><code>&lt;runtime&gt;
      &lt;assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"&gt;
          &lt;dependentAssembly&gt;
              &lt;assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" /&gt;
              &lt;bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.1" /&gt;
          &lt;/dependentAssembly&gt;
      &lt;/assemblyBinding&gt;
  &lt;/runtime&gt;
  </code></pre>
  
  <p>Tried it again, and got the same warnings.</p>
  
  <p>My question is - do I still have a problem?  Or will my  resolve it, despite the warnings?</p>