Blog

How to Fix VirtualBox Not Starting Windows 11: Step-by-Step Solutions

VirtualBox is a popular tool for running virtual machines on your computer. However, sometimes it may not start properly when trying to run Windows 11. This can be frustrating for users who rely on virtualization for testing or development.

There are several reasons why VirtualBox might fail to start Windows 11, ranging from software conflicts to system settings. Fortunately, many of these issues can be fixed with simple steps.

This article will guide you through easy and detailed solutions to get VirtualBox working again with Windows 11. Each step is explained clearly to help beginners and experienced users alike.

By following these instructions, you should be able to resolve most common problems preventing VirtualBox from starting Windows 11.

Quick Note Before You Begin

Before troubleshooting, please check the following to save time:

  • Ensure your system meets the minimum requirements for running Windows 11 in VirtualBox.
  • Verify that you have installed the latest version of VirtualBox from the official website.
  • Make sure Windows 11 ISO or installation media is not corrupted.
  • Confirm that virtualization technology (VT-x or AMD-V) is enabled in your computer’s BIOS/UEFI.
  • Close any other virtualization software like Hyper-V, VMware, or Docker, as they might conflict with VirtualBox.

Step 1: Check Virtualization Support in BIOS/UEFI

VirtualBox requires hardware virtualization features to run 64-bit guest operating systems like Windows 11. These features are called Intel VT-x or AMD-V. If disabled, VirtualBox may fail to start the virtual machine.

How to check and enable virtualization:

  1. Restart your computer and enter BIOS/UEFI settings. This usually involves pressing a key like F2, Del, or Esc during startup. Check your manufacturer’s guide if unsure.
  2. Look for settings labeled “Virtualization Technology,” “Intel VT-x,” “AMD-V,” or similar under CPU or advanced settings.
  3. Enable the virtualization option if it is disabled.
  4. Save changes and exit BIOS/UEFI.

After rebooting, try starting VirtualBox again. Enabling virtualization is crucial because without it, VirtualBox cannot run 64-bit VMs like Windows 11.

Step 2: Disable Hyper-V on Windows 11

Windows 11 includes Hyper-V, a built-in virtualization platform that can interfere with VirtualBox. If Hyper-V is enabled, VirtualBox may not start your Windows 11 VM.

To disable Hyper-V:

  1. Press Windows + R, type optionalfeatures.exe, and press Enter.
  2. In the Windows Features window, uncheck Hyper-V and Windows Hypervisor Platform.
  3. Click OK and restart your computer when prompted.

Alternative method using Command Prompt:

bcdedit /set hypervisorlaunchtype off

Run this command as administrator, then restart your PC.

Disabling Hyper-V frees up virtualization resources for VirtualBox to operate correctly.

Step 3: Adjust VirtualBox Settings for Windows 11

Sometimes, incorrect VM settings can prevent Windows 11 from starting in VirtualBox. Let’s review and adjust key settings.

Memory and CPU Allocation

Assign enough RAM and CPU cores to the VM. Windows 11 needs at least 4 GB of RAM and a dual-core processor for smooth operation.

  • Open VirtualBox, select your Windows 11 VM, and click Settings.
  • Go to the System tab and increase the Base Memory to 4096 MB or more.
  • In the Processor tab, allocate at least 2 CPU cores.

Enable EFI (Special OSes Only)

Windows 11 requires UEFI boot mode. To enable EFI:

  • In VM settings, go to System > Motherboard.
  • Check the box for Enable EFI (special OSes only).

Graphics Controller

Set the graphics controller to VBoxSVGA, which supports Windows 11 better.

  • In VM settings, go to Display > Screen.
  • Set Graphics Controller to VBoxSVGA.
  • Increase Video Memory to at least 128 MB.

After making these adjustments, save the settings and try to start the VM again.

Step 4: Update VirtualBox and Guest Additions

Running outdated VirtualBox versions can cause compatibility issues with Windows 11. Always use the latest VirtualBox release.

To update VirtualBox:

Update Guest Additions: Once Windows 11 VM is running, install or update Guest Additions from the VirtualBox menu Devices > Insert Guest Additions CD image. This improves performance and compatibility.

Step 5: Check for Conflicting Software

Some software can conflict with VirtualBox and prevent it from launching virtual machines. Common culprits include other virtualization tools, antivirus programs, and security software.

What to do:

  • Disable or uninstall other virtualization apps like VMware, Hyper-V (already covered), or Docker.
  • Temporarily turn off antivirus or firewall software to see if they interfere with VirtualBox.
  • Ensure Windows Defender or third-party security tools are not blocking VirtualBox processes.

After making these changes, try starting your Windows 11 VM again.

Step 6: Run VirtualBox as Administrator

Sometimes, VirtualBox needs administrative privileges to access certain system resources.

How to run as administrator:

  • Right-click the VirtualBox shortcut or executable.
  • Select Run as administrator.

If this resolves the issue, you can set VirtualBox to always run as administrator by:

  1. Right-click the VirtualBox shortcut and select Properties.
  2. Go to the Compatibility tab.
  3. Check Run this program as an administrator.
  4. Click Apply and OK.

When Nothing Works

If you’ve tried all the above steps and VirtualBox still does not start Windows 11, consider the following:

  • Reinstall VirtualBox: Uninstall VirtualBox completely and reinstall the latest version.
  • Check VirtualBox Logs: Logs can provide specific error messages. Find logs in the VM folder or via the VirtualBox Manager under Show Log.
  • Visit Official Forums and Support: The VirtualBox community forums (forums.virtualbox.org) are helpful for troubleshooting specific errors.
  • Try Alternative Virtualization Software: If VirtualBox continues to fail, consider using VMware Workstation Player or Microsoft’s Hyper-V as alternatives.

Frequently Asked Questions (FAQs)

Why does VirtualBox say “VT-x is not available” when starting Windows 11?

This means hardware virtualization is disabled in your BIOS/UEFI or another program like Hyper-V is blocking access. Enable virtualization in BIOS and disable Hyper-V to fix this.

Can Windows 11 run in VirtualBox without hardware virtualization?

Windows 11 requires hardware virtualization for 64-bit support and UEFI boot. Without it, you cannot run Windows 11 in VirtualBox effectively.

How much RAM should I allocate to Windows 11 in VirtualBox?

At least 4 GB is recommended, but 8 GB or more improves performance if your host system has enough memory.

What if my VirtualBox VM gets stuck on a black screen?

Try enabling EFI in VM settings, increasing video memory, and checking if virtualization is enabled. Also, update VirtualBox and Guest Additions.

Is it safe to disable Hyper-V for VirtualBox?

Yes, but disabling Hyper-V will prevent Windows features that rely on it, like Windows Sandbox or WSL 2, from working until you re-enable Hyper-V.

Conclusion

VirtualBox not starting Windows 11 can be caused by several factors, but most are fixable with straightforward steps. Ensure virtualization is enabled in BIOS, disable Hyper-V, and configure your VM settings correctly.

Updating VirtualBox, checking for conflicting software, and running the program as administrator often resolves common issues. If problems persist, consult logs and official support channels for more help.

By following this step-by-step guide, you should be able to get your Windows 11 virtual machine up and running smoothly in VirtualBox.

Leave a Reply