Hi Nojan,
Thanks for the quick response. We use source address affinity currently. I don't have any access to the f5, but I can tell you that the network guys used the documentation in the f5 for SAP in SOA guide.
I'm calling it a timeout because it only occurs if I leave the session idle for a certain period of time (about 10 minutes is my best guess). If I open two browser sessions, one using f5 and one direct to the app server and navigate to the same place in both, logged on as separate users, then leave them both idle for 10 minutes, when i come back and click on a link, in the direct session, it goes to that link. When I click a link in the f5 session, I get the error above. It seems to be basically expiring my f5 session more quickly than it expires my direct session. Perhaps there is some kind of keepalive setting on the f5. We typically have two physical servers in the pool for each virtual server. I only get the 500 errors when using the f5, not when using the hostname of the instance in the URL.
Thanks,
Brian