Same issue yesterday, upgrading from 8.8.12 to 8.8.15. No visible admin menu and no NG service running while correctly setup (and they were running in 8.8.12). First try was to redeploy all the zimlets, didn't work. We had to do a "yum update" on all mailstores to get it back. Did you try ...

Are you using the correct package to install?
Which command line did you use?
Is your server able to go on the internet (DNS resolution and https access)?

Try with another browser on your mobile client.

With 8.8.12 NE and "touch client" enabled, on an android phone, I'm getting good results with chrome/iron but bad with fennec.

Check (and double check) the dumpster variables for your accounts/CoS.
If dumpster is enabled but never purged, you can get this kind of storage issue.

Barry posted this this morning in the Zeta mailing-list, if you're using the Zeta Alliance Nextcloud Zimlet. Upon upgrading you will see a Network Service Error. To make you web interface reachable again, remove openzal: rm /opt/zimbra/lib/ext/ownCloud/zal.jar and restart mailbox. There seems to be ...

It's an old page (2016) and it's in french (sorry) but here you have informations about using the free version of Tyk as proxy/cache to the VT API.
https://blog.zenithar.org/post/2016/01/ ... irustotal/

https://forums.zextras.com/zextras-migration-tool/1916-zxmigtool-2-4-12-not-compatible-zimbra-ose-8-8-15-a.html#post8205 Officially, ZxMig is not working as an export tool for server running ZCS 8.7.11 and newer. You have to use the ZeXtras backup tool. However, you can export from older servers wit...

The DoSFilter is not related to MTA but mailboxd.

IIRC, it's not just about apache, the "_" is not DNS compliant.
https://www.quora.com/Why-are-underscor ... host-names

Found it.
https://bugzilla.zimbra.com/show_bug.cgi?id=106916

This fixes the problem for us and others.
viewtopic.php?f=15&t=66201