ASP.NET Session "cross-threading" Issues
I remember reading this article back in July and it finally bit me with an application that a consultant finished up here a few months ago. The fix is now applied, we’ll see if it works.
Too bad it took me a week to remember where I had read the fix. *sigh*
Session state and kernel-mode output caching don’t mix. If you use session state in a page that has output caching enabled, and if the application runs on IIS 6.0, then you need to turn off kernel-mode output caching. You’ll still get the benefit of output caching, but because kernel-mode output caching is substantially faster than ordinary output caching, the caching won’t be as effective.