IIS ASP.NET Session is lost

Question

I know that this has been asked several times, but in the web config we set the

<sessionState timeout="2880"></sessionState>

the app pool recycle is 1740 minutes, the application pool timeout is also 1740 mins now, ping and rapid fail protection is turned off, and in the global.asax we log every application start, session start/end, application error. I see 2 "application start" than 2 "session start" in the logs, nothing changes, a few minutes later, we get a new "application start" (2 of them again) with 2 "session start"-s, with the same sessionid as before (no "session end" in between). The result is a web application that quits every few minutes.

Answer 1

Not sure about this, but how many instance of the application do you allow?

Under IIS>Application Pools>YourAppPool>Advanced Settings;

you'll find relevant settings:

• idle time-out (set to 0?)
• Disable Overlapped Recycle (this might be your culprit;a new instance starts before the old one is disposed?)

Another thing i can think of is 'Service Throttling' on your binding, or perhaps there are multiple Sessions or Instances allowed?