Denis, You make an excellent point.
I can confirm that until today the system was running 3.27.22 (I just restored the backup to be sure). So the problem was definitely on 3.27.22. I cannot rule out 100% that the issue was not as a direct result of this version, however a few months ago I moved to DB sessions as this was happening occasionally and we would have been on earlier versions - but we have just did 2 large sends (1 of 250 the other of 550) with tokens and the number of reported issues was around 10% - 15%. This could be due to the larger numbers. But either way - it shouldn't be happening at all.
Session Expired as far as I know is all to do with cookies (please correct me if i'm wrong). I know there is a weird issue with Plesk that clears the default cookie path on the hour as part of a system cron script (even if they have not expired).
So I thought there is two choices .. either:
- Change the cookie save path to something not default (add a cron job to clear them every 6 hours) OR
- Use the DB Sessions built into LS (this seemed the simpler and safest way as its part of LS already)
I can and will switch the the non default Session_Save_Path - but wondered if someone would chip in with a "Eureka! Moment"