You can change the max request length in the web. config file
<httpRuntime maxRequestLength="102400" />
Bear in mind that users will still be limited by bandwidth issues and may receive timeout errors.
You can put something like this in your Global.asax file to handle the errors in a more friendly manner:
protected void Application_Error(object sender, EventArgs e)
{
Exception sourceException = Server.GetLastError().InnerException != null ? Server.GetLastError().InnerException : Server.GetLastError().GetBaseException();
if (sourceException.Message.Equals("Maximum request length exceeded.") && Request.ContentType.Contains("multipart/form-data"))
{
HttpContext.Current.Server.ClearError();
string path =//specify page to redirect to
HttpContext.Current.Response.Redirect(path);/*in casini just get cannot connect page, but in iis get appropriate page*/
}
}