I got a tiny problem. We had ZCS 5.0.11 FOSS, then I upgraded directly to 6.0.2 FOSS, no problems showed up, all working fine for a couple of days.
In my own account I had set up an external account way back, which polled the mails automatically, but one day it suddenly stopped. I only changed the behaviour regarding signatures, I cannot tell if that was the same day.
I did check the settings with "zmprov gds myaccount" and everything is like it was before, the settings within the UI seem to be ok too. My account is the only one affected, all other users having the same setup got no problems, so I don't think it has something to do with the upgrade.
Thanks in advance