I have this classic ASP site which has been working fine until we updated it. It was just a site-update, meaning .asp files which ran fine in our test enviroment, no service packs or patches. I can not reproduce the error at all on a test-site on the same server.
The system it’s running on is IIS6 on Server 2003.
Somehow, it has now started to behave weird when a user revisit the site with an old session-cookie, which makes the site not running Session_OnStart() again.
Since the session is long gone, it leaves me with an empty Session()-scope, which breaks a lot of code on the site.
I have never seen this behaviour before, since I would assume that visiting a site with an old session-cookie would retrigger Session_OnStart?
It seems like our upgrade, which was a cache-functionality that stored data in the Application-scope somehow broke the session-handling.
Even though the information regarding memory-limits for the Application- and Session-scope always says that it’s resource-dependant, somehow using a lot of memory in the Application-scope breaks something.
We’re talking about around 100-200MB of data, when I store it in files instead the issue seems to go away silently. Leaving this answer for future references in similar cases.