Current issues in ZCS 8.6
Current (Known) Issues in ZCS 8.6 Build 1153
Upgrading from 8.5.1 to 8.6 doesn't check the local proxy variables and it fails the upgrade. When upgrading, the Script validates the license against https://license.zimbra.com. If your Server is behind a proxy the upgrade script (and also the license activation itself) ignores the Proxy System Variable.
Mac Outlook 2011 requires 3DES or RC4 ciphers Outlook 2011 is unable to negotiate SSL/TLS, probably from disabling RC4 and/or other insecure ciphers With a workaround in the same Bug.