参考地址https://www.cnblogs.com/zemax/p/5607561.html
方式一：
1.建一个类，如下

using System;
using System.Web.Mvc;
using System.Web.Routing;
 
namespace CheckInManagerSystem.Controllers
{
    public class CheckLogin : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            if (filterContext.HttpContext.Session != null)
            {
                if (filterContext.HttpContext.Session.IsNewSession)
                {
                    var sessionCookie = filterContext.HttpContext.Request.Headers["Cookie"];
                    if ((sessionCookie != null) && (sessionCookie.IndexOf("ASP.NET_SessionId", StringComparison.OrdinalIgnoreCase) >= 0))
                    {
                        filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary(new { Controller = "Account", Action = "LogOff" }));//这里是跳转到Account下的LogOff,自己定义
                    }
                }
            }
        }
    }
}

2.在每个用到session的Action前增加这个[CheckLogin()]，如

[CheckLogin()]
public ActionResult Details(int userid)
{
　　ViewDataLoad();
    return View(_context.GetUserById(userid));
}

这样就OK啦！不会再因为session过期而报红页面了！
方式二
2022-7-25更新
同样的内容往往可能遇到很多次，而遇到很多次往往处理方式也不净是相同的逻辑，小编本想写一篇文章但是发现之前就写过，所以干脆写在一个地方吧

public ActionResult WebIndex()
{
	if (Session["Account"] != null)
	{
	    AccountModel account = new AccountModel();
	    account = (AccountModel)Session["Account"];
	    string DepName = sysUserBLL.GetStructNameByUserId(account.Id);
	    ViewBag.UserName = account.TrueName;
	    ViewBag.DepName = DepName;
		//正常视图逻辑
		//...
	}
	else
	{
	    return RedirectToAction("Index", "Account");
	}
}