I'm new to viBoot but already a big fan. I'm running it on a W10 Pro laptop, and have created a couple of VMs from Reflect images (W10 and W7).

I've been using Hyper-V Manager to launch my VMs for a few days now, making changes, and wanted to take a backup of the current state. That's when I realised that the VMs are not actually visible in viBoot anymore (if they ever were).

The registry entry that viBoot reads on startup (when 'Refreshing virtual machines list, namely "HKLM\Software\Macrium\viBoot\Machines\0"') points to a single image location, so all I get in the "Virtual Machines" pane is one entry of "Unassigned Virtual Disks", and in the "Mounted Images" pane the filepath of that one image. In Hyper-V Manager I still see all my VMs just fine.

Has the registry maybe got garbled when I've been switching between Hyper-V Manager and viBoot? And if so, can I edit it to get viBoot back in sync?

Thanks to Anshul from Macrium, we worked through a support ticket and established that Hyper-V checkpoints were the root cause of the VMs disappearing from viBoot.

It turns out that Hyper-V on Win10 enables 'use automatic checkpoints' by default for each VM, and as each checkpoint is a Hyper-V format differential disk (.avhdx), viBoot could no longer see the attached VM. Deleting the checkpoints, letting Hyper-V merge the differential disk(s) into the base, then refreshing within viBoot made the VM reappear.

Hyper-V checkpoints have their uses, but I will be turning off 'use automatic checkpoints' in almost all cases.

Nice find.  Hopefully viBoot can be updated to disable that feature by default for the VMs it creates.  I do understand the rationale for automatic checkpoints -- if you royally mess up your VM, you can just click Revert to bring it back to its pre-startup state -- but I would rather not have it for my purposes, because I take checkpoints when I need them, and I'd rather avoid the performance penalty they introduce at other times. But most frustrating of all is that Microsoft doesn't provide a way to manage this setting on a global basis.  It's enabled for all new VMs on Client Hyper-V and disabled for all new VMs on Server Hyper-V, with no way to change that default behavior on either platform.  I've lost track of how many times I've created a new VM to quickly install Windows in order to test something and then discovered upon shutdown that it has to merge everything I just did into the main VHDX file because of that stupid checkpoint.