VirtualBox : Cannot enable nested VT-x/AMD-V without nested-paging and unresricted guest execution!

 Got this error after I enabled nested virtualization on my vm (was working previously):

Solution:https://github.com/GNS3/gns3-gui/issues/3032

1. run this at command prompt: bcdedit /set hypervisorlaunchtype off
2. turn off windows feature "Virtual Machine Platform" *Hyper-V)
3. reboot