Why is HttpContext.Session null when redirectMode = ResponseRewrite
问题 As is suggested elsewhere, I am using redirectMode = ResponseRewrite in my custom error configuration so my custom error page can access the exception info. This has worked like a charm for some time. In adding some more "help the user recover from an error" type functionality, we need a piece of info that has been previously stored in Session. When implementing this, I found that the various avenues to Session end in null when redirectMode=ResponseRewrite, but they are all populated when