Hyper-V virtual machines do not start after using Startup Repair

Over the weekend, I attempted to reconfigure some of the drives in my Hyper-V server at home.  Note that I said “attempted”.  I ran into hardware issues and ended up having to revert back to my old configuration - but somehow in all of this – I broke my system disk.

Specifically it would not boot any more.

This did not phase me because I knew that the excellent startup repair tool in Windows would soon have me up and running – which it did.

But I was surprised to find that when my system did finally boot – none of my virtual machines started up.  When I tried to start the virtual machines manually, I was informed that the hypervisor was not running.

After scratching my head for a moment, I realized what had happened.  Startup repair had rebuilt my boot configuration data store to get my system up and running.  But it did not know that Hyper-V needs to have some specific settings enabled in the boot configuration data store in order to start the hypervisor.

I quickly opened an administrative command prompt and ran the following command:

bcdedit /set hypervisorlaunchtype auto

After that I rebooted the system and successfully started my virtual machines.