So if worse comes to worse, I can just clean install and readd my VMs. I just want to see if there's a way to do this.
My understanding is that Server 2016 can do an inplace upgrade to Server 2019, wherein local settings are saved and the core OS is upgraded.
Based on that, I tried with my HyperV 2016 servers. The setup ran, however, it kicks me out with an error after some time regarding a CD key can't be applied.
I did some searching, and this is an issue with Windows Server if you don't have key applied.
However, 2016 and 2019 HyperV do not have CD keys that I can see, and I can't find any way to resolve this online.
Has anyone run into this before?
Best Answer
It's a known issue... Not just inplace from an existing HYPERV but from any windows server.
I got it working by setting the server to boot from USB and that USB was the hyperv install disk (used rufus with MBR instead of GPT).
Before I skipped boot from that USB and it would always give me that error.
It might not be a general solution but might help someone out there.