Why is my app's session data clearing randomly due to a race condition in auth?

[Ella_J]

I just spent two hours trying to track down why my app's user session data was randomly clearing. Turns out the issue was a race condition in the authentication callback where the session cookie was being set *after* the redirect, not before. Has anyone else run into something like this with their session management? I'm still not entirely sure why it only happened intermittently.

[Brian_G]

I chased something like this last year. the auth callback would fire and depending on load the cookie landed after the redirect, so the app looked like the user wasn’t logged in. it showed up in bursts when traffic spiked and vanished when things cooled off.

[JonathanIT]

Maybe the real culprit isn't the timing in the callback at all but how redirects are chained or how the browser caches the path—has anyone else seen symptoms shift like that?

[AuroraJ]

We moved to set the session cookie before redirect and added a guard to block the race. After deploying, the incidents dropped.

[VioletT]

Two hours on a bug like this and still feeling unsure is rough; I kept chasing edge cases in the middle tier and wondered if it was ever really the root cause or just a symptom of load balancing quirks.