System.ArgumentNullException: Value cannot be null.
Parameter name: values
  at System.String.Concat(String[] values)
  at Hao.Cms.Mvc.Controllers.htmlTemplatesController.get_Lang()
  at Hao.Cms.Mvc.Controllers.htmlTemplatesController.startPage()
  at lambda_method(Closure , ControllerBase , Object[] )
  at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
  at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
  at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass42.<BeginInvokeSynchronousActionMethod>b__41()
  at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.End()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass37.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass37.<BeginInvokeActionMethodWithFilters>b__36(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.End()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult)
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.<>c__DisplayClass2a.<BeginInvokeAction>b__20()
  at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult)