Need Advice on Upgrading 2016 Servers to 2019

Honestly, if it were me, I’d build new servers rather than trying to upgrade the old ones. Upgrading just moves potential problems over. Building fresh lets you document everything properly and allows you to keep your old servers as a backup until everything's confirmed to be working.

Before you dive in, it's worth asking why you're choosing 2019 instead of going for newer options like 2022. How many servers are you upgrading, and what specific roles do they serve? Just something to think about as you make your plans.

If you're looking to do an in-place upgrade, it's pretty straightforward. Backup everything first, download the new ISO, and run it on your server. Just check to ensure you don't have any roles that might block the upgrade. And, if you're managing multiple servers, handle the ones that won't upgrade last. Good luck out there!

I'd suggest aiming for Server 2022 instead. It supports TLS 1.3, which is a nice security upgrade, and also has extended support which lasts longer. Plus, the upgrade process should be smoother with newer servers.

Honestly, 2019 is already past mainstream support. If you're virtualized, I'd recommend building fresh servers on 2022 or even 2025, if possible, and migrating your services to them. It's usually easier and gives you a cleaner slate! But if you're set on upgrading, definitely make sure to check what software you're running first to ensure compatibility before proceeding.