asp.net mvc actionresult即使在页面刷新后仍保留参数值？

I am setting an error Message in the viewbag to show to the user after each postback how ever I do not want to show this error message on page reload or refresh. I have tried to set it to null but it still is shown because the json parameter still contains the values of the first submit.I am setting an error Message in the viewbag to