System.NullReferenceException: Object reference not set to an instance of an object.
   at Umbraco.Web.Mvc.MasterControllerFactory.ReleaseController(IController controller)
   at System.Web.Mvc.MvcHandler.<>c.<BeginProcessRequest>b__20_0(AsyncCallback asyncCallback, Object asyncState, ProcessRequestState innerState)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallBeginDelegate(AsyncCallback callback, Object callbackState)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.Begin(AsyncCallback callback, Object state, Int32 timeout)
   at System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state)
   at System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state)
   at System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData)
   at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerAsyncWrapper.<>c__DisplayClass2_0.<BeginProcessRequest>b__0()
   at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.Wrap[TResult](Func`1 func)
   at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerAsyncWrapper.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData)
   at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride)
   at System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage)
   at System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm)
   at System.Web.HttpServerUtilityWrapper.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm)
   at System.Web.Mvc.Html.ChildActionExtensions.ActionHelper(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues, TextWriter textWriter)
   at System.Web.Mvc.Html.ChildActionExtensions.Action(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues)
   at Our.Umbraco.DocTypeGridEditor.Web.Extensions.HtmlHelperExtensions.RenderDocTypeGridEditorItem(HtmlHelper helper, IPublishedContent content, String editorAlias, String viewPath, String previewViewPath)
   at ASP._Page_app_plugins_doctypegrideditor_render_doctypegrideditor_cshtml.Execute()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
   at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
   at Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model)
   at ASP._Page_Views_Partials_grid_editors_base_cshtml.Execute()