Win10 Pro/Hyper-V cannot start any machines, "failed to power on: system cannot find the path specified"

Windows 10 Pro, v1803 Build 17134.648, 64-bit. Hyper-V Manager v10.0.17134.1.

I have had Hyper-V running on my Windows 10 machine for many months, but recently have had an error when starting my VMs up: Microsoft VmBus (Instance ID [long GUID]): Failed to Power on with Error 'The system cannot find the path specified.'.

(Note: I have moved my default Virtual Hard Disks and Virtual Machines folders to a harddrive that is not my C: due to space limitations.)

(clarification) While Hyper-V can see existing and new VMs, it cannot start any of them without throwing the above error. This applies to machine that pre-existed prior to the first error, or were newly created using Quick Create (with default settings.) There are no devices in the VM settings that indicate they are in error, and the VHD is found in the location the settings indicate it should be.

I have no idea what the path is that it's claiming it cannot find. I can find confirmation in the Event Logs, but no additional clues. In Applications and Services Logs/Microsoft/Windows/Hyper-V-Worker/Admin, I see the two error event IDs 12010 ['Windows 10 Dev Environment' Microsoft VmBus: Failed to Power on with Error 'The system cannot find the path specified.' (0x80070003).] and 10230 ['Windows 10 Dev Environment' failed to start.].

Can someone please give me a clue where I can look to confirm what "path specified" it's looking for, and how I can provide it, or change it?

Thanks to all who tried to help, but I have since abandoned this entirely. I have purchased a new machine, which I will be installing a new Windows 10 environment onto, and will start Hyper-V completely from scratch on that box, then after confirming that Hyper-V functions correctly, I will import my VMs to there.