We just upgraded our main Zimbra server from 8.0.7 -> 8.6.0.
Before the upgrade, all our CardDAV clients were able to connect, no problem.
After the upgrade, none of them do.
The Zimbra logs show for example
==> nginx.log nginx.access.log
Error 502 Connection to Upstream is Refused
HTTP ERROR 502
Problem accessing ZCS upstream server.
Cannot connect to the ZCS upstream server. Connection is refused.
- upstream server is unreachable
- upstream server is currently being upgraded
- upstream server is down
Please contact your ZCS administrator to fix the problem.
Powered by Nginx-Zimbra://
I guess we need to change something in configuration somewhere. What to do here?