What is the best way to upgrade an HA pair from 12.x to 14.x in a production environment?

Hello Matt!

Welcome to the foruns! Glad you're here.

I would not upgrade to v14 yet. This release did not reach the stability version (14.1.1) so you could hit some bugs. Version 13 have already reached it (v13.1.1.4 or older).

One way to see if the upgrade and how to do that is generating a qkview from the standby box and upload it to ihealth. Inside ihealth you have a menu called "Upgrade Advisor" that can pretty much help you with that.

Some rules of thumb are:

1. Before ever trying to upgrade, backup your entire environment and do failover tests to make sure your apps are correctly configured. Adjust what needs to be adjusted.
2. We usually start the upgrade on the standby box. When it's up and running we fail all the traffic-groups to it and test everything. Once we are satisfied, we then go and upgrade the othe box.
3. After both boxes are upgraded, test both of them as active to make sure everything is smooth.

Pro tip 1: Make sure your devices have active support contracts before you start. In case you need F5 help during the procedure. You can check that here: https://secure.f5.com/validate/validate.jsp.

Pro tip 2: On some old boxes you have to check the "last check date". Please read this carefully before trying to upgrade: https://support.f5.com/csp/article/K7727

Best of luck!

Cheers! Rafael