Due to some special circumstances, SigintOS does not work as EFI boot. You need to turn off the EFI feature when booting the ISO file with VirtualBox.
![](https://www.sigintos.com/wp-content/uploads/2023/11/VirtualBox-Efi-Boot.png)
You will encounter this error when EFI Boot is on.
You can use Settings -> System section to turn off EFI Boot
![](https://www.sigintos.com/wp-content/uploads/2023/11/VirtualBox-Efi-Settings.png)
When you turn off the EFI feature from the settings, you will see this screen with Legacy Boot.
![](https://www.sigintos.com/wp-content/uploads/2023/11/VirtualBox-Efi-Boot-Fixed.png)