Fix the VirtualBox “No bootable medium found! System halted” Error

The message “FATAL: No bootable medium found! System halted” appears when VirtualBox starts a virtual machine but cannot find anything to boot from. There is no mounted installation ISO and no virtual hard disk that holds a usable operating system. It shows up most often on a brand-new VM, but it can also hit an existing machine if the virtual disk is missing, empty, or wrongly configured.

Quick answer: Open the VM’s Settings > Storage, attach a valid bootable ISO to the Controller: IDE (not SATA), then in System > Motherboard set the correct boot order and start the machine again.

Why the “No bootable medium found” error happens

VirtualBox checks its boot devices when a VM powers on. If none of them contain a loadable operating system, it stops with this error. A few specific conditions cause it.

Cause	What is happening
No ISO or OS attached	A new VM was created but no bootable installation ISO was mounted, and the virtual disk is still empty.
ISO on a SATA controller	The installation ISO was mounted to a SATA controller. SATA works for virtual hard drives, but a bootable ISO needs the IDE controller.
Wrong or corrupt ISO	The disc was burned as data only, the ISO download is corrupt, or the wrong architecture image was selected (for example arm64 instead of amd64).
UEFI guest without EFI enabled	The disk holds a UEFI-based OS such as Windows 10 or 11, but EFI is turned off in the VM.
Invalid boot configuration	A cloned or converted disk is missing its boot loader or its boot files are damaged, common after using Disk2vhd or CloneVDI.
Boot order disabled	Booting from the hard disk was switched off in the System boot order, so the installed OS is skipped.

Note: This problem is specific to VirtualBox and can occur on any host, whether Windows, macOS, or Linux.

Fix 1: Attach a bootable ISO to the IDE controller

This is the fix when you are installing an operating system into a fresh VM. Before you begin, make sure you have a valid, uncorrupted ISO. If you are unsure, download a fresh copy from the official source, such as the VirtualBox downloads page for the program itself, and verify the ISO checksum against the value listed on the OS vendor’s site.

Select the virtual machine in VirtualBox, then click Settings. You can also right-click the VM and choose Settings from the menu.

Go to the Storage section. If there is no IDE controller, click the Adds new storage controller icon and choose Add IDE Controller.

With the IDE controller selected, click the Adds optical drive icon and choose Choose disk. Click Add, browse to your downloaded ISO, select it, and click Choose.

Tick the Live CD/DVD checkbox and set the optical drive as IDE Primary Master. Then open System and drag the Optical entry to the top of the boot order so the VM boots from the ISO first.

Click OK, start the VM, and follow the on-screen prompts to install the operating system.

Tip: If you created the VM with the wrong OS type, the error can persist. When making a Linux VM, set the type to Linux and the version to your distribution, since picking Windows by mistake produces the same halt.

Fix 2: Boot from an existing virtual hard disk

If you already installed an OS, or you downloaded a ready-made VDI image, the VM must point to that disk rather than expect a new empty one.

When creating the VM, at the virtual hard disk prompt choose Use an existing virtual hard disk file and select your VDI with the file picker. Do not create a new blank disk if you intend to run an existing one.

Open Settings > Storage and confirm the VDI is attached to an IDE or SATA port under the controller.

After an install finishes, remove the installation ISO from the virtual optical drive so the machine boots from the hard disk instead of the empty installer media.

In System > Motherboard, make sure the Hard Disk is checked and listed as the first boot device, since a disabled hard-disk boot entry causes the halt even when the OS is present.

Fix 3: Enable UEFI for Windows 10 and 11 guests

A virtual disk that holds a UEFI-based operating system will not start under legacy BIOS. Turn on EFI so the firmware matches the disk.

Open the VM’s Settings and go to System > Motherboard.

Confirm the Hard Disk is checked and is the first boot device. Under Extended Features, enable Enable I/O APIC and Enable EFI (special OSes only), then click OK.

Start the VM. If it still fails to boot, disable EFI again and move on to repairing the boot configuration. VirtualBox only supports the combinations legacy BIOS with MBR and UEFI BIOS with GPT, so a mismatch between firmware and partition scheme will keep failing.

Fix 4: Repair boot files on a cloned or converted disk

When you convert a physical machine into a VHD or VDI with tools like Disk2vhd or CloneVDI, the boot loader can be left behind or damaged. In Windows, the boot loader usually lives on a small “System Reserved” partition, not on the C: partition, so cloning only C: produces an unbootable disk. Rebuild the boot files using BCDBOOT.

Attach a bootable Windows ISO using Fix 1, then boot the VM from it. If it will not boot from the ISO, temporarily disable EFI in System > Motherboard.

At the Windows Setup screen, press SHIFT + F10 to open a command prompt, or choose Next > Repair your computer > Troubleshoot > Advanced Options > Command Prompt.

Identify the System partition and assign it a drive letter. Note the System partition’s size, then match it under list volume.

diskpart
select disk 0
list partition
list volume
select volume 2
assign letter=Z
exit

Replace the volume number with the one that matches your System partition. Then rebuild the boot data.

bcdboot C:\windows /s Z: /f ALL

For a UEFI guest, use bcdboot C:\windows /s Z: /f UEFI instead.

Shut down the VM, go to System, and set the Hard Disk as the first boot device. Start the VM. If it stops with “FATAL: INT18: BOOT FAILURE”, re-enable I/O APIC and EFI in the settings.

How to confirm the fix worked

The error is resolved when the VM moves past the black halt screen and either loads the installer from the ISO or boots straight into the installed operating system. If you reach the OS desktop or the setup wizard, the boot device is now valid.

If the halt returns, the most common reasons are an ISO mounted to SATA instead of IDE, a corrupt or wrong-architecture ISO, the hard disk left out of the boot order, or a firmware-and-partition mismatch between BIOS/MBR and UEFI/GPT. Walk back through the fix that matches your setup, correct that one detail, and the machine will boot.