title: Could not load type 'System.Web.Optimization.StyleBundle'
body: <p>Sometimes after build and launch my MVC4 web app I got this error.
  It can dissapear after rebuild or not.
  Same issue I got after publish to Windows Azure.</p>
  <p>Does anybody know how to fix this error?</p>
  <pre><code>Server Error in '/' Application.
  
  Could not load type 'System.Web.Optimization.StyleBundle' from assembly 'System.Web.Optimization, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.
  
  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.TypeLoadException: Could not load type 'System.Web.Optimization.StyleBundle' from assembly 'System.Web.Optimization, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.
  
  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.
  
  Stack Trace: 
  [TypeLoadException: Could not load type 'System.Web.Optimization.StyleBundle' from assembly 'System.Web.Optimization, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.]
     Inventarium.Web.Mobile.App.BundleConfig.RegisterBundles(BundleCollection bundles) in c:\dev\Inventarium\Inventarium.Web\Inventarium.Web.Mobile.App\App_Start\BundleConfig.cs:30
     Inventarium.Web.Mobile.App.MvcApplication.Application_Start() in c:\dev\Inventarium\Inventarium.Web\Inventarium.Web.Mobile.App\Global.asax.cs:18
  
  [HttpException (0x80004005): Could not load type 'System.Web.Optimization.StyleBundle' from assembly 'System.Web.Optimization, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.]
  System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode(HttpContext context, HttpApplication app) +4058245
  System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +191
  System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +352
  System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +407
  System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +375
  
   [HttpException (0x80004005): Could not load type 'System.Web.Optimization.StyleBundle' from assembly 'System.Web.Optimization, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11703488
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4870277
  </code></pre>