Enable I/O APIC & UEFI in VirtualBox.

The fatal error “INT18 BOOT FAILURE” in VirtualBox, commonly appears when you attaching a VHD/VHDX/VMDK file which contains an UEFI operating system. To fix this problem just proceed and enable UEFI on the VirtualBox machine’s settings. To do that:

1. Press the X button to close the VM machine window and Power Off the machine.

2.  Open the VM Settings and go to System > Motherboard.

3. Here ensure that the Hard Disk is checked and is the first boot device, and at Extended features check the following two (2) options and click OK:

   • Enable I/O APIC
   • Enable EFI (special OSes only)
4. Try to start the Virtual Machine now. Hopefully it will start without error now.

Disable Hyper-V on Host machine

1. Navigate to Control Panel > Programs and Features > Turn Windows features on or off
2. Uncheck the following features and click OK to apply the change:
   • Containers
   • Hyper-V
   • Virtual Machine Platform
   • Windows Hypervisor Platform
   • Windows Sandbox
3.  Restart the computer after uninstall.
4. Open Command Prompt as Administrator.
5. Type the following command and press Enter:
   • bcdedit /set hypervisorlaunchtype off
6. Reboot your PC again.
7. After reboot, start the VirtualBox VM machine and see if the problem is fixed.

Fix Boot Problems

1. Open the Settings of the VirtualBox machine and go to Storage.
2. Click the 1st plus (+) button next to Controller to add optical drive.
3. Click Add and find and open the Windows.iso file.
4. Then select the Windows.iso file and click Choose.
5. After attaching the Windows.iso file in Storage device go to System and drag Optical to the top in order to boot the VM from the attached Windows.iso.
6. Also, make sure that the “Enable EFI” option is unchecked, otherwise you will not be able to boot from the ISO file. When done, click OK.
7. Start the Virtual Machine and click Next > Repair Your computer.

8. Then select Troubleshoot > Startup Repair.

9. Allow the Startup Repair to run and depending on the result do the following actions:

   • If the Startup Repair can fix the problem, shutdown the virtual machine, set the hard disk as first boot device and try to start again the virtual machine.

   • If the Startup Repair cannot fix the problem, continue to next step.

10. Click Advanced Options and go to Troubleshoot > Command Prompt.

11. In Command prompt give the following commands in order (press enter after each command)

    • diskpart
    • select disk 0
    • list partition
12. Now notice the size of the System partition (e.g. 100MB in this example).
13. Then type the following command and find out the volume number of the System partition by using its size as a reference.
    • list volume
14. Now give the following commands to select the system partition (using its volume number), and to assign the drive letter Z: to it. Then exit DISKPART:
    • select volume x    *     Change the Volume number “x” according your case.
    • assign letter=Z
    • exit
15. Finally, in command prompt give this command to repair the boot files:
    • bcdboot C:\windows /s Z: /f ALL
16. Close all windows, shutdown the virtual machine, set the hard disk as first boot device and start the virtual machine.