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Force Stopping VirtualBox VM

When working with VirtualBox, you might encounter a frustrating situation where a Virtual Machine (VM) gets stuck in the "stopping" state and becomes unresponsive to normal shutdown commands. This often happens due to the VM becoming unresponsive, the host system running out of memory, VNC connections failing, or normal shutdown commands timing out.

This guide will walk you through forcefully, stop it on an Ubuntu host server. By following these steps, you'll be able to regain control of your VMs and prevent further issues.

Prerequisites​

To follow this guide, you will need:

  • Root/sudo access to the Ubuntu host server
  • SSH access to the VirtualBox host
  • A VM that is stuck in "stopping" or a similar unresponsive state

Step-by-Step Procedure​

Step 1. Identify the Problem VM​

First, list all VMs to find the problematic one:

VBoxManage list vms

Step 2. Check VM State​

Verify the current state of the stuck VM:

VBoxManage showvminfo "VM_NAME" | grep "State"

Example output: State: stopping (since 2026-02-09T11:09:02.590000000)

Step 3. Check Running VMs​

Confirm which VMs are actually running:

VBoxManage list runningvms

Step 4. Attempt Normal Force Stop (Optional)​

Try the normal force stop command first:

VBoxManage controlvm "VM_NAME" poweroff

This may fail with error: "The virtual machine is being powered down"

Step 5. Find and Kill the VBoxHeadless Process​

If normal force stop fails, identify the stuck process:

ps aux | grep -i "VM_NAME"

Look for VBoxHeadless processes with high CPU/memory usage

Step 6. Force Kill the Process​

Kill the stuck VBoxHeadless process:

sudo kill -9 [PID]

Replace [PID] with the actual process ID from step 5

Step 7. Verify Process Termination​

Confirm the process is gone:

ps aux | grep -i "VM_NAME"

Should only show the grep command itself

Step 8. Check VM State​

Verify the VM state has changed:

VBoxManage showvminfo "VM_NAME" | grep "State"

State should change to "aborted" or "powered off"

Step 9. Restart VM (When Ready)​

Once the VM is properly stopped, you can start it again:

VBoxManage startvm "VM_NAME" --type headless

Important Notes​

Data Loss Warning: Force killing a VM will result in loss of any unsaved data in RAM. Only use this method when:

  • The VM is completely unresponsive
  • Normal shutdown methods have failed
  • You're prepared to lose current memory state

Memory Management: If the host was running low on memory (97%+ usage), consider:

  • Stopping other non-essential VMs first
  • Monitoring host memory usage before restarting
  • Adjusting VM memory allocations if needed

Troubleshooting Tips​

  • If kill -9 doesn't work immediately, wait a few seconds and check again
  • Multiple VBoxHeadless processes might exist for the same VM - kill all of them
  • After force stopping, always verify the VM state before attempting to restart
  • Consider checking VirtualBox logs if problems persist: /var/log/vbox/

Conclusion​

Force stopping a VirtualBox VM should always be a last resort, used only when the VM is completely unresponsive and normal shutdown methods have failed. While it resolves the immediate problem of a stuck VM, it's crucial to be aware of the potential for data loss in RAM. By carefully following the steps outlined in this guide. Identifying the VM, checking its state, and precisely killing the associated VBoxHeadless process. You can effectively manage unresponsive VMs on your Ubuntu host. Always remember to verify the VM's state afterward and investigate underlying causes like memory constraints if the issue recurs.

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