Cannot request Schema - Byte validator missing

System.ArgumentNullException: Value cannot be null.
Parameter name: items
at System.Web.Mvc.MultiSelectList..ctor(IEnumerable items, String dataValueField, String dataTextField, IEnumerable selectedValues)
at Unify.Connect.Web.Areas.Extensibility.Views.InsightPanelledConnector._Page_Areas_Extensibility_Views_InsightPanelledConnector_CreateOrEdit_cshtml.Execute()
at ASP._Page_Areas_Extensibility_Views_InsightPanelledConnector_CreateOrEdit_cshtml.Execute() in c:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\02600b40\d5b161f8\App_Web_createoredit.cshtml.ff9a2f64.gtmfdkmb.0.cs:line 0
at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
at System.Web.WebPages.StartPage.RunPage()
at System.Web.WebPages.StartPage.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 System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<>c__DisplayClass1e.<InvokeActionResultWithFilters>b__1b()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)