This is a strange phenomenon reported by users of one of our applications where all users are forced to log back in at the same time. This happens during data entry causing loss of data. I'm assuming it's only started happening since we upgraded to 4.2 from 4.0 because I've never heard of such behaviour before the upgrade and this app has been used for a couple of years now.
I've not done much in the way of diagnosis yet, just wondering if anyone here can shed some light on what might be happening (if anything). A few users corroborated the story yesterday, apparently every user session seems to expire at exactly 4pm each day. Due to users reporting a similar issue last week, I extended the "Maximum Session Length" to 10 hours from 8 hours, assuming they started work early and it simply decided their session was too old. I also set the "Maximum Session Idle Time" to 0, as the inline help says this will disable this feature.
Is there any other mechanism that kills user sessions? I vaguely remember reading a post here from one of the gurus that there is some internal session cleanup that happens every 8 hours and that this job overrides any other preference for session management that may have been configured.