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Windows 11 Application Guard is a security feature designed to protect your device from malicious websites and files by isolating the browser session in a separate environment. However, sometimes this feature may not work as expected, causing frustration and potential security risks.

If you find that Application Guard is not functioning correctly, don’t worry. There are several straightforward ways to troubleshoot the issue and get it back up and running smoothly.

This guide will walk you through the process step-by-step, starting from the simplest fixes to more advanced options. By following these instructions carefully, you can restore Application Guard’s functionality and enhance your device’s security.

Let’s begin by checking some quick prerequisites to ensure your system is ready for Application Guard.

Quick Note: Prerequisites and Initial Checks

• Windows 11 Edition: Application Guard is available only on Windows 11 Pro, Enterprise, or Education editions. It is not included in Windows 11 Home.
• Hardware Requirements: Your device should support virtualization technology (Intel VT-x or AMD-V) and have it enabled in the BIOS/UEFI.
• Windows Updates: Ensure your Windows 11 is up to date. Application Guard improvements and fixes are often included in system updates.
• Browser Compatibility: Application Guard currently works with Microsoft Edge. Using other browsers may cause it not to function.

Step 1: Verify Application Guard is Enabled

The first and simplest step is to check if Application Guard is enabled on your device. Sometimes, it might be turned off or never activated.

1. Click on the Start button and type Windows Features.
2. Select Turn Windows features on or off from the search results.
3. Scroll down and look for Windows Defender Application Guard.
4. Ensure the checkbox next to it is checked. If it is not, check it and click OK.
5. Restart your computer to apply changes.

Why this matters: Application Guard will not work if it is not enabled. This setting activates the necessary components on your system.

Step 2: Confirm Virtualization is Enabled in BIOS

Application Guard relies on hardware virtualization to create isolated environments. If virtualization is disabled, the feature won’t work.

1. Restart your computer and enter the BIOS/UEFI settings. This usually involves pressing a key like F2, Del, or Esc during startup (check your PC’s manual).
2. Look for settings related to Intel Virtualization Technology (VT-x) or AMD-V.
3. Make sure virtualization is enabled.
4. Save and exit BIOS settings. Your PC will restart.

Why this matters: Without virtualization enabled, Application Guard cannot isolate browser sessions effectively, preventing it from functioning.

Step 3: Enable Required Windows Services

Application Guard depends on specific Windows services. If these are disabled, it may stop working.

1. Press Windows + R to open the Run dialog box.
2. Type services.msc and press Enter.
3. In the Services window, locate the following services:
• Hyper-V Host Compute Service
• Windows Defender Application Guard Service
4. Right-click each service and select Properties.
5. Set the Startup type to Automatic and click Start if the service isn’t running.
6. Click Apply and then OK.

Why this matters: These services handle the virtualization and isolation processes behind Application Guard; they must be active for it to work.

Step 4: Reset Microsoft Edge Application Guard Settings

If Application Guard is enabled but still not working, resetting its settings in Microsoft Edge can help.

1. Open Microsoft Edge.
2. Click the three dots (…) in the upper-right corner and select Settings.
3. Navigate to Privacy, search, and services.
4. Scroll down and click Address bar and search.
5. Look for Application Guard related options and reset or toggle them off and on.
6. Restart Microsoft Edge.

Alternative method: You can also reset Edge completely by going to Settings > Reset settings > Restore settings to their default values. This can clear corrupted configurations affecting Application Guard.

Step 5: Check Group Policy Settings

Application Guard settings can be controlled via Group Policy. Incorrect policies might disable or block it.

1. Press Windows + R, type gpedit.msc, and press Enter.
2. In the Group Policy Editor, navigate to:
• Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Application Guard
3. Check the policies such as Turn On/Off Application Guard. Make sure they are either Not Configured or set to Enabled.
4. If you make changes, restart your PC.

Why this matters: Group Policy settings override local options and can disable Application Guard if misconfigured.

Step 6: Run Windows Security Troubleshooter

Windows includes built-in troubleshooters that can automatically detect and fix issues related to security features.

1. Open Settings by pressing Windows + I.
2. Go to System > Troubleshoot > Other troubleshooters.
3. Find Windows Security and click Run.
4. Follow the on-screen instructions to complete the troubleshooting process.

Why this matters: The troubleshooter can detect conflicts or missing components that you might not easily spot.

When Nothing Works

If you have tried all the above steps and Application Guard still does not work, consider these final options:

• Perform a System File Check: Open Command Prompt as administrator and run sfc /scannow to fix corrupted system files.
• Reset or Reinstall Windows 11: As a last resort, resetting Windows or performing a clean installation can resolve deep system issues.
• Consult Official Microsoft Support: Visit the Microsoft Application Guard FAQ and Support page for additional help.

Frequently Asked Questions (FAQs)

What is Windows Defender Application Guard?

It is a security feature in Windows 11 that isolates browser sessions and certain apps in a secure virtual environment to protect your system from malware and attacks.

Why is Application Guard not available on my Windows 11 Home edition?

Application Guard is only available on Windows 11 Pro, Enterprise, and Education editions because it requires advanced security and virtualization features not included in Home editions.

How do I know if virtualization is enabled on my PC?

You can check virtualization status using Task Manager under the Performance tab. It will indicate if virtualization is enabled or disabled.

Can I use Application Guard with browsers other than Microsoft Edge?

No, Application Guard currently works only with Microsoft Edge. Other browsers are not supported.

Will enabling Application Guard slow down my PC?

Application Guard uses virtualization, which may use some system resources, but on modern PCs the impact on performance is usually minimal.

Do I need administrator rights to enable Application Guard?

Yes, enabling Application Guard and changing related system settings require administrator privileges.

Conclusion

Windows 11 Application Guard is a valuable security feature designed to protect your device by isolating risky activities. If it stops working, following a series of simple troubleshooting steps can often restore its function quickly.

Start by ensuring Application Guard is enabled and your system supports virtualization, then move on to verifying services, policies, and browser settings. Using the built-in Windows troubleshooters can also save time.

By addressing these areas methodically, you can resolve common problems and keep your device protected with Application Guard. Remember, if all else fails, official Microsoft resources and support are there to assist you.