session_name("login");
session_start();

if (!isset($_SESSION['UserId'])) {
    if(!header("Location: https://subdomain.mywebsITe.COM/"))
    { die("Unauthorized access"); }
}

session_regenerate_id(); 
$UserId = $_SESSION['UserId'];

问题是我说有一个页面

Register > Select Service > Select Payment Mode

假设在付款模式下,用户意识到他在第2页输入错误,选择服务,他按下后退按钮,由于会话的使用而发生错误.

错误是

Document Expired

This document is no longer available.

The requested document is not available in Firefox's cache.

    As a security PRecaution,Firefox does not automatically re-request sensitive Documents.
    Click Try Again to re-request the document From the website.

我应该如何处理此类事件,我想使用会话来保护我的页面,但我也希望用户能够在不损害会话的情况下返回上一页.