Windows update caused MVC3 and MVC4 stop working

The best solution is update DLL to version 4.0.0.1. Try use nuget:

Install-Package Microsoft.AspNet.Mvc -Version 4.0.40804 -Project <your project name>

This will automatically update

You just have to edit version System.Web.Mvc manually in:

<compilation debug="true" targetFramework="4.0">
  <assemblies>
    <add assembly="System.Web.Mvc, Version=4.0.0.1, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

We had to manually touch each .csproj to update the version from 4.0.0.0 to 4.0.0.1 to get our builds going. Quite a pain.

New references should look like:

<Reference Include="System.Web.Mvc, Version=4.0.0.1, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" />

Had the same issue after update:

Security Update for Microsoft ASP.NET MVC 4.0 (KB2993928) http://support.microsoft.com/kb/2993928

But only for project with a reference to the System.Web.Mvc, not installed by package. My colleague, who hadn't installed Microsoft ASP.NET MVC 4.0 Runtime and didn't received the update, had no trouble and had still the reference to 4.0.0.0, not to 4.0.0.1 I manually changed the reference to 4.0.0.1, after check-in, my colleague could still build with a reference to 4.0.0.0. (Working both on Win7 Pro SP1, VS2013 Pro Update 3)

Please see this blog, the recommended way is to update corresponding NuGet package:

http://blogs.msdn.com/b/webdev/archive/2014/10/16/microsoft-asp-net-mvc-security-update-broke-my-build.aspx

To quote:

The problem can be resolved by implemented one of the following solutions: (Preferred) Install Microsoft.AspNet.Mvc from the NuGet gallery (this will install a binding redirect in your web.config). You can do this from the NuGet package manager or the NuGet console inside Visual Studio: Install-Package Microsoft.AspNet.Mvc -Version -Project PROJECTNAME MVC 4 version: 4.0.40804.0 MVC 3 version: 3.0.50813.1 Manually update the reference to System.Web.MVC.dll (don’t use the one in the GAC). Try the Add Reference -> Assemblies -> Extensions dialog box.

See this: Microsoft Asp.Net MVC Security Update MS14-059 broke my build! MS blogged about it since it obviously brought a lot of confusion

For web project, you may have to update the configuration in the web.config as well:

  <dependentAssembly>
    <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35"/>
    <bindingRedirect oldVersion="1.0.0.0-4.0.0.0" newVersion="4.0.0.1"/>
  </dependentAssembly>

You need to change all the references to System.Web.Mvc within your solution. Just delete them and add the new 4.0.0.1 version.

Also in the properties change copy local to true.

And in the web.config add the assambly binding to point to the new version of mvc:

    <runtime>
        <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
            <dependentAssembly>
                <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" culture="neutral" />
                <bindingRedirect oldVersion="0.0.0.0-4.0.0.1" newVersion="4.0.0.1" />
            </dependentAssembly>
        </assemblyBinding>
    </runtime>

Okay,

For me it was two simple steps:

First I changed all references to System.Web.Mvc from 4.0.0.0 to 4.0.0.1,

Then I had to go to the properties of System.Web.Mvc (possibly because I had removed and re-added it) and change copy local to true.

Hope this is helpful for somebody.

If you are still getting the same error after trying @Krzysztof solution or any of the other answers above, one work around that might work for you is to uninstall MVC Runtime 4.0