HTTP Handlers are mainly used to handle the requests caused by the user or by an error and we will handle it by navigating to some other location or with some other message.

For defining HTTP Handlers first the entry will be made in Web.Config file

<httpHandlers>
    <add verb="*" path="*.cspx" type="CspxHandler"/>
</httpHandlers>

This means any kind of .cspx type call will be handled by the handler we defined in our Web.Config file.

 public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "text/plain";

        if (context.Request.RawUrl.Contains(".cspx"))
        {
            string newUrl = context.Request.RawUrl.Replace(".cspx", ".aspx");
            context.Server.Transfer(newUrl);
        }
    }