解决方法
Application domain recycled when
Sub-Directories are deleted,that’s why your session will lost and you are redirected to the login page.
有关更多详细信息,请从MSDN博客查看本文,并阅读为什么应用程序域回收?从这里
ASP.NET Case Study: Lost session variables and appdomain recycles
并检查这一个Deleting ASP.NET 2.0 Application Sub-Directories Shuts Down the AppDomain