ASP.NET C# Session Variables Being Lost

I had the same issue before, I keep on losing the my session variables (although not in the same context as yours). I found this articles helpful for my issue: ASP.NET Case Study: Lost session variables and appdomain recycles and PRB: Session Data Is Lost When You Use ASP.NET InProc Session State Mode. Hope it might help you too. Cheers!

Are you calling Session.Abandon() anywhere in the code? I was doing this at the start of my Web App to ensure I was starting with a "fresh" session. Turns out that any Session variables stored even after the "Abandon" would be dropped (even if the SessionID was forced to remain the same via other means, such as using Server.Transfer(Url, true) rather than Response.Redirect), upon postback.

i.e. I could trace into my app, watch all the session variables be correctly set, and then the moment any event handler (anything with AutoPostBack="True", like a checkbox or button on an UpdatePanel) was called, BAM, I had the same SessionID, but zero session variables.

Removing the pre-emptive call to Session.Abandon() solved my problem straightaway.

Jeff