Clear bootstrap modal on browser back button click in ASP.Net

Hi everyone I have a problem with client. RegisterStartupScript: I created this event to make sure that every time there is an error a bootstrap modal appears.

My problem is that when I go to another page and go back to the previous page, the modal is visible, I would like this behavior not to occur and I tried to use js but it fails and I would prefer to do it code behind side.