I've just started migrating from Exchange 2007 to Zimbra 8.6 on CentOS 7.5 and I've run into this issue. All services are running, I can get to the admin page of the Web GUI just fine. I was working through the installation tasks and set up a test account then tried to access the webmail. The login screen appears just fine, but after logging in I get a long wait followed by the time out message below. I've tried the test account and my admin account - same result. I've disabled SELinux on the server and I'm stumped! This didn't happen when I installed a test server with an evaluation license last year (Sadly, I've deleted that VM now).
Could anyone shed some light?
BTW, this is the licensed version.
HTTP ERROR 504
Problem accessing ZCS upstream server. Reason: Cannot connect to the ZCS upstream server. Connection timeout.
- upstream server is blocked by a firewall
- upstream server is failing to send back the response in time
- upstream server is down
Please contact your ZCS administrator to fix the problem.
Powered by Nginx-Zimbra://