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How to Start a Virtual Machine in Oracle VirtualBox

Learn how to start an existing virtual machine from VirtualBox Manager or by opening its .vbox configuration file.

Oracle VirtualBox is desktop virtualization software used to create and run virtual machines (VMs). A VM is a software-defined computer that runs a guest operating system using virtual hardware. This guide explains how to start an existing VM.

You must create or import a VM before you can start it. Installing VirtualBox alone does not create a machine to boot.

Confirm That a Virtual Machine Is Available

Open Oracle VirtualBox Manager. VirtualBox Manager is the main application window for viewing, configuring, and controlling registered VMs.
Look at the list of registered machines in the Manager window.
Confirm that the VM you want to run appears in the list. Its entry may show details such as the operating system type, assigned memory, and current state.

If the list is empty, create a new VM or import an existing one first. A VM that exists only as disk files may also need to be registered with VirtualBox before it appears in the Manager.

Start a VM from VirtualBox Manager

Launch VirtualBox Manager.
Click the VM entry for the guest system you want to start.
Click the Start button in the main toolbar.
Wait while VirtualBox initializes the VM's virtual hardware and begins booting the guest operating system.

The guest operating system should open in a separate VM window. It does not run directly inside the list of machines in VirtualBox Manager. After the boot process reaches a login or setup screen, interact with the guest normally. For example, select a user account, enter a password, or complete the operating system's initial setup.

Example: Starting a registered machine

Open VirtualBox Manager.
Select the VM named for the desired guest system.
Click Start.
Wait for the guest OS boot screen, then continue with the normal guest login.

Start a VM by Opening Its .vbox File

Each VirtualBox machine has a .vbox file. This is the machine settings file that identifies the VM and stores its configuration, such as virtual hardware settings and attached storage references.

VirtualBox normally stores machines in a VirtualBox VMs directory under the current user's home folder. The exact location depends on the host operating system and VirtualBox configuration. Users can configure a different default machine folder, so the VM may be stored elsewhere.

Open the host operating system's file manager.
Navigate to the configured VirtualBox VMs directory, or to the custom machine folder used by VirtualBox.
Open the subfolder whose name matches the VM you want to start.
Find the file ending in .vbox.
Double-click the .vbox file.
Verify that the VM window opens and that the guest operating system begins booting.

This file-opening method is associated with machines created by VirtualBox 4.0 or later. If the file does not open the expected machine, use VirtualBox Manager to locate and verify the registered VM instead.

Example: Starting from a machine folder

Open the user's VirtualBox VMs directory.
Open the folder matching the target machine.
Locate the file with the .vbox extension.
Double-click the file and confirm that a separate VM window appears and begins booting.

Ways to Start a VirtualBox Virtual Machine

Method: VirtualBox Manager method

Where to begin: The VirtualBox Manager window

Primary action: Select the registered VM and click Start

Expected result: A separate VM window opens and the guest operating system boots

Notes: The VM must be registered and selected before Start can be used

Method: Open .vbox file method

Where to begin: The configured VirtualBox VMs directory or another machine folder

Primary action: Open the target machine's .vbox settings file

Expected result: VirtualBox opens the machine and starts its guest operating system

Notes: Check the custom machine folder if the VM is not in the usual location; this method is associated with VirtualBox 4.0 or later

What Happens After Startup?

After you start a VM, VirtualBox performs several operations:

It opens the VM in its own window.
It initializes virtual hardware such as the processor, memory, display adapter, storage controller, and network adapter.
It presents the configured boot device to the guest.
The installed guest operating system boots. The guest OS is the operating system installed inside the VM.

The VM remains running until you shut it down, power it off, save its state, or pause it. Closing the VM window may display choices for how to stop the machine, so read those choices carefully before confirming.

Starting Versus Pausing a VM

Starting boots a VM that is powered off or otherwise not running. Pausing is different: it temporarily suspends execution while keeping the guest operating system in memory. A paused VM is not shut down, and it can usually resume from the point at which it was paused.

After the guest is running, you may also install Guest Additions. Guest Additions are optional software installed in the guest OS to improve host-guest integration, including display resizing, mouse input, clipboard sharing, and other features. They are related to the running VM but are not required to click Start.

Troubleshooting Startup

The Start button cannot be used

Verify that a VM entry is selected in VirtualBox Manager.
Confirm that the machine is registered and available rather than missing or inaccessible.
If the Manager list is empty, create or import a VM before attempting to start one.

The expected .vbox file is not found

Check whether VirtualBox uses a custom machine folder instead of the usual VirtualBox VMs directory.
Open the folder belonging to the VM rather than searching only the default location.
Enable file-extension display in the host file manager so that the .vbox ending is visible.

Opening a .vbox file does not boot the intended VM

Confirm that the selected .vbox file belongs to the correct VM folder.
Open VirtualBox Manager and verify the machine's name, configuration, and current state.
Avoid selecting a settings file from a similarly named machine directory.

The VM window opens but the guest does not finish booting

Read the guest OS boot messages for errors.
Review the VM settings and verify that it has appropriate assigned resources.
Confirm that the VM has a valid boot device and that its virtual disk or installation media is attached as expected.
Distinguish a guest OS boot problem from a failure to launch VirtualBox itself: if the VM window opens, VirtualBox has launched and the problem is likely during virtual hardware initialization or guest boot.

Key Terms

Oracle VirtualBox: Desktop virtualization software used to create and run virtual machines.
VirtualBox Manager: The main VirtualBox application window used to view, configure, and control registered virtual machines.
Virtual machine: A software-defined computer that runs a guest operating system using virtual hardware.
Start button: The VirtualBox Manager toolbar control used to boot the selected virtual machine.
.vbox file: The VirtualBox machine settings file that identifies and stores configuration for a virtual machine.
VirtualBox VMs folder: The default or configured host-side directory that contains folders for VirtualBox virtual machines.
Guest operating system: The operating system installed inside the virtual machine.
Guest Additions: Optional software installed in a guest OS to improve display, input, clipboard, and other host-guest integration features.
Pause: A VM state in which execution is temporarily suspended without shutting down the guest operating system.

Exam-relevant note: The usual startup sequence is to select a registered VM in VirtualBox Manager and click Start. The guest OS then boots in a separate VM window. The .vbox file is the machine's settings file, not the guest OS's virtual hard disk.