How to Start a Virtual Machine in Oracle VirtualBox

Learn how to start an existing virtual machine in Oracle VirtualBox Manager or by opening its .vbox machine definition file.

What Starting a Virtual Machine Does

Starting a virtual machine (VM) powers on its configured guest operating system. The guest operating system is the operating system installed inside the VM, while the host operating system is the system running Oracle VirtualBox.

Starting is different from other VM operations:

Creating a VM defines virtual hardware and prepares a new machine.
Importing a VM adds a machine that was packaged or created elsewhere.
Pausing temporarily freezes a running guest.
Saving stores the current session so it can be resumed later.
Shutting down uses the guest operating system's normal power-off process.

Before you start, the VM must already be registered in VirtualBox, or you must have access to its VirtualBox machine definition file. A machine definition file normally ends in .vbox and contains the VM's configuration.

Ways to Start a VirtualBox Virtual Machine

Method	When to use it	Starting point	Expected outcome
VirtualBox Manager Start control	The VM is already registered and appears in the Manager list.	Select the VM and choose Start.	A separate VM display window opens and the guest starts or resumes.
Opening a `.vbox` machine definition file	The VM is not visible in the current Manager list, but its complete machine folder is available.	Open the intended `.vbox` file in the VM folder.	VirtualBox opens or registers the machine and begins startup in a VM window.

Start a VM from VirtualBox Manager

Open Oracle VirtualBox Manager. This is the main graphical interface for listing, configuring, and starting registered VMs.
Find the desired machine in the list of registered virtual machines.
Select the machine entry. Check its name and displayed state so that you do not start a different VM by mistake.
Click the Start button in the Manager toolbar.
Wait for the separate VM display window to open. The guest then follows its normal startup process.

For example, to boot a registered Linux VM, open VirtualBox Manager, select the Linux VM, click Start, and wait for the guest login screen in the new VM window.

Start a VM by Opening Its .vbox File

A .vbox file is a VirtualBox machine definition file. It stores configuration information such as the VM name, virtual hardware, and references to virtual storage. It is not usually the guest's complete storage by itself; associated virtual disk files must also be available.

Find the folder containing the intended VM. A common default location is the VirtualBox VMs folder inside the current user's home folder.
Open the VM's directory and identify the file ending in .vbox.
Confirm that the file belongs to the intended machine before opening it.
Open the .vbox file using the file manager. VirtualBox opens or registers the machine, and the guest begins starting in a VM display window.
Verify that the displayed guest is the expected operating system.

The exact location may differ. The VM folder may have been moved, or a custom default machine folder may have been configured. If the VM was copied or moved, locate its complete folder rather than opening an unrelated configuration file.

Safe practice: Do not launch a copied or moved .vbox file if its associated virtual disks are missing. The configuration may refer to storage paths that no longer exist.

What to Check After Startup

After you click Start or open the machine definition file, confirm that a VM display window appears. Normal guest boot indicators can include:

Firmware or hardware initialization messages.
A boot menu.
An operating-system logo or loading screen.
The guest operating-system login screen.

Click inside the VM display to direct keyboard and pointer input to the guest. When input appears trapped in the guest window, review VirtualBox's host-key behavior to return control to the host.

Guest Additions are optional software installed inside the guest. They can improve display resizing, pointer integration, shared clipboard behavior, and other usability features after the guest has started. Learn more in VirtualBox Guest Additions.

Understand the VM State Before Starting

A VM's state describes its current condition. The result of Start depends on that state.

VM state	What Start does	User-visible result
Powered Off	Powers on the configured virtual hardware and begins a regular boot sequence.	Firmware, boot devices, and the guest operating system load from the beginning.
Saved	Restores the previously saved session.	The prior desktop or application session may return without a complete guest boot.
Paused	A paused machine should be resumed rather than treated as a newly started machine.	The frozen guest continues from its paused point.
Running	Cannot be started a second time from the same registration.	Use the existing VM display window instead.

For a saved-state example, select the VM in Manager and click Start. VirtualBox can restore the previous desktop session instead of showing the full firmware-to-login boot sequence.

If you need to understand the difference between pausing and other state changes, see pausing a virtual machine. When finished, use the guest's own shutdown process whenever possible rather than abruptly powering off the VM.

Practical Startup Checklist

Confirm that the VM has already been created or imported.
Check whether it is registered in VirtualBox Manager.
If it is registered, select the correct entry and click Start.
If it is not registered, locate the complete VM folder and open the intended .vbox file.
Wait for the VM display window and observe the guest boot indicators.
Click in the display when you need to use the guest keyboard or pointer.
Confirm that the host has enough available memory, processor capacity, and storage resources.
Make sure no conflicting VirtualBox session is already using the same VM.

Troubleshooting Startup Problems

The Start control is unavailable or the wrong machine starts

Likely cause: No VM is selected, or a different VM entry is highlighted.
Likely cause: The VM is already running or otherwise unavailable.
Resolution: Select the correct machine entry, check its displayed state, and use the existing VM window if it is already running.

Opening a .vbox file does not start the expected guest

Likely cause: The incorrect .vbox file was opened.
Likely cause: The VM folder was moved or copied.
Likely cause: The configuration refers to virtual disk files that are missing or stored elsewhere.
Resolution: Confirm that the configuration belongs to the intended VM, locate the complete VM folder and required disk files, then open or register the correct machine configuration.

The VM window opens but the guest does not boot

Likely cause: The guest has no bootable operating system or installation medium.
Likely cause: The configured boot order does not point to a bootable device.
Likely cause: The VM has a hardware or resource configuration problem.
Resolution: Review storage and boot settings, confirm that the guest disk or installation medium is attached, read any VirtualBox error message, and check available host resources.

Keyboard or mouse input behaves unexpectedly

Likely cause: Focus is not in the guest display.
Likely cause: Guest Additions are not installed or are outdated.
Resolution: Click inside the VM display, review host-key behavior, and install or update Guest Additions after the guest is running.

Related VirtualBox Tasks

If the VM is not yet available, review how to create a virtual machine or learn about moving a virtual machine. For missing or detached storage, see virtual disks and disk image files. You can also review installing a guest operating system when the VM has not yet been bootstrapped.