Recover Hyper-V VM stuck in the "Restoring" state

If you have a Hyper-V VM which is stuck in the "Restoring" state, perform the following steps:

1. Right-click the Start menu > Run > services.msc.
2. Locate and double-click Hyper-V Virtual Machine Management.
3. Set Startup type to Manual.
4. Restart the PC. This may take a while. Don't switch off the PC!
5. Once rebooted, navigate to C:\ProgramData\Microsoft\Windows\Hyper-V\Virtual Machines by typing or pasting that path into the navigation bar at the top of an Explorer window.
6. Locate and rename the .VMRS file to add an extra character, e.g. A at the start of the filename.
7. Leave that Explorer window open for now, as you'll need it later.
8. Right-click the Start menu > Run > services.msc.
9. Locate and double-click Hyper-V Virtual Machine Management.
10. Set Startup type to Automatic.
11. Click the Start button in that window.
12. Click OK.
13. Rename the .VMRS file back to the original name.
14. Open Hyper-V Manager using its shortcut on the taskbar.
15. Right-click the IPOPP VM in the list and choose Delete Saved State.
16. The status will change a couple of times, then the State will change from Saved to Off.

You should now be able to start the VM again.

To prevent this from happening, ensure the VM is shut down cleanly and the PC is shut down cleanly.