Oracle Virtualbox

How to Open and Use the Log Viewer in Oracle VirtualBox

Learn how to open the Oracle VirtualBox Log Viewer for a selected virtual machine and inspect warnings, errors, and diagnostic information.

Oracle VirtualBox is desktop virtualization software used to create and run virtual machines (VMs). A virtual machine is a software-based computer running inside VirtualBox. When a VM fails to start, behaves unexpectedly, or reports a device or configuration problem, its logs can provide useful clues.

What the VirtualBox Log Viewer Does

The Log Viewer is a VirtualBox interface for viewing diagnostic log information associated with one selected VM. It can display warnings, errors, and other messages generated while that VM starts or runs.

These messages are useful when investigating:

  • Virtual machine startup failures
  • Problems that occur while the VM is running
  • Virtual device or hardware-related issues
  • Configuration problems

Prerequisite: Identify and Start the VM

For the primary procedure, power on the target VM first. Starting the VM helps ensure that the Log Viewer contains recent information from the session in which the problem occurs.

  1. Open Oracle VirtualBox Manager, the main graphical interface for selecting and managing VMs.
  2. Identify the VM you want to investigate.
  3. Power on that VM. If you are investigating a startup problem, note what happens when the VM starts.
  4. Return to VirtualBox Manager while the VM is running, or after reproducing the issue.

If you need help starting a VM, see how to start a virtual machine.

How to Open the Log Viewer

Use the following navigation in VirtualBox Manager:

VirtualBox Manager > select virtual machine > Machine > Show Log
  1. Open Oracle VirtualBox Manager.
  2. Select the relevant virtual machine in the manager window. Select the affected VM, not merely a VM with a similar name.
  3. Open the Machine menu. This menu contains actions for the currently selected VM.
  4. Choose Show Log.
  5. Confirm that the Log Viewer window opens for the selected VM.

The displayed logs now relate to the VM that was selected when you used Machine > Show Log.

How to Review Warning Information

Read through the entries shown in the Log Viewer and look for messages marked as warnings or errors. A warning signals a potential issue or unusual condition that may require attention. An error usually indicates a more direct failure or operation that VirtualBox could not complete.

  • Focus on entries recorded around the time the problem occurred.
  • Look for messages that mention the affected device, operation, or configuration.
  • Note the exact error or warning text before changing settings.
  • Record related context, such as whether the VM was starting, running, paused, or being shut down.
  • Compare newer entries with older entries when determining whether the message is related to the current problem.

For example, if a VM fails during startup, start it, observe the failure, open its Log Viewer, and inspect the newest entries near that attempt. If a running VM shows a device problem, inspect entries generated at the time the device stopped working.

Example: Check a Running VM for Warnings

  1. Start the VM.
  2. Use VirtualBox Manager to select that same VM.
  3. Choose Machine > Show Log.
  4. Review the displayed entries for warnings and errors.
  5. Write down useful messages and their surrounding context before continuing with troubleshooting.

Example: Compare an Affected VM with Another VM

Suppose one VM has a problem while another works normally. Select the affected VM in VirtualBox Manager first, then open Machine > Show Log. The resulting messages describe the selected machine and can guide later investigation of its settings, devices, or startup behavior.

Opening the log for the working VM instead may produce valid log information but not information about the problem you are investigating.

Troubleshooting the Log Viewer

The log information belongs to the wrong VM

Likely cause: A different VM was selected before the Log Viewer was opened.

Resolution: Close the viewer if necessary, select the intended VM in VirtualBox Manager, and choose Machine > Show Log again.

The log does not contain useful information

Likely cause: The VM was not powered on, or the issue did not occur during the session being inspected.

Resolution: Power on the VM, reproduce the issue when appropriate, then reopen the Log Viewer and inspect the newest relevant entries.

Show Log is unavailable or does not work as expected

Likely cause: No VM is selected in VirtualBox Manager.

Resolution: Select the target VM first, then open the Machine menu and choose Show Log.

Key Points to Remember

  • The Log Viewer displays diagnostic and warning information for an individual VM.
  • Power on the target VM before following the main procedure so recent activity can be recorded.
  • Select the correct VM in VirtualBox Manager before opening its logs.
  • Use Machine > Show Log to open the viewer.
  • Inspect warnings and errors that match the time of the problem.
  • Record messages and related context before making further troubleshooting changes.

For broader VirtualBox guidance, see the Oracle VirtualBox online course or review topics such as virtual machine settings when available in your learning materials.