Gotta Love the gottchas

So here’s the story. I have a test Hyper-V cluster of 5 nodes - all HP Proliant DL 380 G7 connected to HP MSA2040 and HP P2000 arrays.
It’s been working quite fine as a test environment. Recently I’ve decided to update drivers and firmware to newest version available in SPP P03093_001_spp-Gen8.1-SPPGen81.4 (2019 edition).

Patching went well, nodes rebooted, cluster operational, failvoer cluster manager working and reporting no issues, VMs running.
Then a few days later I try to export a running VM. I (try to) connect using Hyper-V and get:

Hyper-V

Well, I check with FailoverCluster as see no issues. 3 out of 5 servers are operating normally.
I try to restart vmms service

Restart-Service vmms

Still no go. Let’s try and reboot the server :grin:

Restart-Computer TestHyperv1 -Protocol WSMan -Wait -force

A quick search and I get to this thread from 2015. A slightly different error, but provided by Brian Ehlert fix works. Running as administrator below command works:

MOFCOMP %SYSTEMROOT%\System32\WindowsVirtualization.V2.mof

Now, I need to find out WHAT caused the issue and WHY only on 2 out of 5 identical nodes :evil: