If you encounter this hyper-v error when starting the VM:

[Window Title]
Hyper-V Manager

[Main Instruction]
An error occurred while attempting to change the state of virtual machine XXX.

‘Unnamed VM’ failed to initialize.

An attempt to read or update the virtual machine configuration failed because access was denied.

[Expanded Information]
‘Unnamed VM’ failed to initialize. (Virtual machine F55B965C-A88E-4260-B962-CA6D9154A7C5)

‘Unnamed VM’ failed to read or update the virtual machine configuration because access was denied: General access denied error (0x80070005). Check the security settings on the folder in which the virtual machine is stored. (Virtual machine F55B965C-A88E-4260-B962-CA6D9154A7C5)

Use this command to setting up the missing security of the VM (using command prompt):

icacls “%SYSTEMDRIVE%\ProgramData\Microsoft\Windows\Hyper-V\Virtual Machines\F55B965C-A88E-4260-B962-CA6D9154A7C5.xml” /grant “NT VIRTUAL MACHINE\F55B965C-A88E-4260-B962-CA6D9154A7C5”:F /l

Remember to replace F55B965C-A88E-4260-B962-CA6D9154A7C5 with your own VM ID.

Try to start again your VM, and it should be running as usual.