Oracle VirtualBox users will finally be able to use Windows 11

Oracle VirtualBox users can now finally use Windows 11 after the company addressed a known issue that caused virtual machine failures whenever Hyper-V or the Windows Hypervisor were installed.

The failures were the reason Microsoft set up safeguards for Windows 11, essentially preventing the users from upgrading. Since Oracle fixed these issues, Microsoft announced it has now removed the safeguards. 

Source