days ago I tried to upgrade Zextras in my system:

UBUNTU 16.04.4
Zimbra 8.8.6.GA.1906

from 2.6.3 to 2.14.

But I get this "Unable to comunicate" error in the Web Administration of Zimbra. I'm sorry I didn't check details or logs, because I panicked, I immediatly tried to update Ubuntu (it had lot of upgrades pending) and also Zimbra to the latest 8.8.11_GA. But again, same message.

Then I did roll back to my snapshot before upgrade Ubuntu & Zimbra, uninstalled Zextras 2.14 and reinstalled 2.6.3. Then It worked as usual.

Somebody knows about a specific issue about this? What I should do instead of what I did?

PS: if I have to download an older versione of Zextras, where I can found it? I was lucky I left the install files of 2.6.3 on my server... but if I did not have it? I found just the 2.4.12 but it's oldest... https://www.zextras.com/it/download-legacy/

PPS: maybe I can try to re-create the issue... if so, which logs I have to check exactly?