Cisco Unified Communications Manager and Unity Connection 12.5

[Dieselboy]

Some points to note here about the 12.5 version of these two applications.

CUCM

CUCM requires minimum ESXi version to be 6.5 U2.
VMware VM properties, need to make sure the network adapter is VMXNET3.
After upgrade, you can shutdown the VM and update the VM version to 13 as well as set the VM OS type to "CentOS 7 64-bit".

CUCM now uses CentOS 7 (not Red Hat RHEL).

With regards to software licensing, it appears that during my upgrade, Cisco have updated their access to download the 12.5 software. So, even though I have valid contracts and valid licenses, Cisco.com downloads tells me "additional entitlement required" and I am unable to download. I have open TAC for this, but not much progress.
For ESXi licensing, I did use PUT to upgrade my vmware esxi 5.x to 6.x which should take 24-48 hours. So far it's been over 6 days and no licenses - so I'd recommend doing this asap, although you get 60-days eval period.

CUC

This one was the most problematic for me for two reasons:
1. Documentation is sparse for the upgrade and is not well-defined or clear.
2. The documentation that is there has been partly copied from the 11.x upgrade guide and so at the time of writing this, does not actually list any supported upgrade paths to version 12.x.

Locale
The guide does not mention this but you need to remove any installed locales. Follow the normal procedure to do this, which means stopping connection mixer and connection manager services on each node before removal. This was discovered by running the cuc pre-upgrade test CLI command on the cuc pub.

COP file install required
Before the upgrade you need to install the .cop file. The guide only states "determine if you need to install a cop and do so" but there is no guidance on how to make this determination. In fact, the pre-upgrade test above does tell you in the output "no cop required" so be wary of this. If you go to the downloads section for CUC you will find the cop files. At the moment there are 3 and the descriptions on all say that you need to install them before the upgrade. You only need to install the latest one. There is no detail whether you need to install this cop on only the publisher of the cluster, so I did install it on each node.

Version switching
In my case I upgraded from 11.5.1 to 12.5. Once TAC provided some guidance that was missing in the guides, I proceeded to upgrade the publisher and selected NOT to reboot / not to switch version after upgrade. However, the system automatically switched to the 12.5 version. I believe this is because it is a "refresh upgrade" and the underlying OS was changed from RHEL6 to CentOS7, however this event did not occur with the cucm upgrade, so this is one to be aware of also. I was able to switch version manually myself for CUCM.

Finally, if you still cant access the software downloads then you'll need to raise a tac to get them to publish the software for you which consumes extra time.