title: An exception of type 'System.InvalidOperationException' occurred in System.Web.Mvc.dll but was not handled in user code
body: <p>I had working code on VS 2013 NET4.5. After update (VS 2013, NET 4.5.1) of NuGet packages I got this error</p>
  
  <blockquote>
    <p>An exception of type 'System.InvalidOperationException' occurred in
    System.Web.Mvc.dll but was not handled in user code</p>
    
    <p>Additional information: The given filter instance must implement one
    or more of the following filter interfaces: IAuthorizationFilter,
    IActionFilter, IResultFilter, IExceptionFilter.</p>
  </blockquote>
  
  <p>I am sure that I implemented <strong>IActionFilter</strong> interface, so how can I get error like this and how can I fix it?</p>
  
  <p>FYI:</p>
  
  <pre><code>public class WWWActionFilterAttribute : System.Web.Mvc.ActionFilterAttribute, System.Web.Mvc.IActionFilter
      {
          public override void OnActionExecuting(System.Web.Mvc.ActionExecutingContext filterContext)
          {
              System.Uri Address = filterContext.HttpContext.Request.Url;
  
              string[] domains = Address.Host.Split('.');
  
              if (domains.Length == 2)
              {
                  System.UriBuilder AddressBuilder = new System.UriBuilder(Address);
  
                  AddressBuilder.Host = string.Format("www.{0}", AddressBuilder.Host);
  
                  filterContext.HttpContext.Response.Redirect(AddressBuilder.Uri.AbsoluteUri);
              }
              else
              {
                  base.OnActionExecuting(filterContext);
              }
          }
      }
  </code></pre>
  
  <p>Config</p>
  
  <pre><code>public class FilterConfig
      {
          public static void RegisterGlobalFilters(System.Web.Mvc.GlobalFilterCollection filters)
          {
              filters.Add(new System.Web.Mvc.HandleErrorAttribute());
              filters.Add(new TIKSN.HomeWebsite.Generalization.WWWActionFilterAttribute());
              filters.Add(new TIKSN.HomeWebsite.Globalization.LanguageActionFilterAttribute());
          }
      }
  </code></pre>