Cannot Turn On Windows Defender in Windows 8.1

I struggled to turn on Windows Defender in my Windows 8.1 operating system.

Uninstall Third-party Antivirus Software

If you cannot turn on Windows Defender in Windows 8.1, it may be because you have third-party antivirus software installed on your computer. To resolve this issue, you will need to uninstall the third-party antivirus software.

Here’s how to uninstall third-party antivirus software in Windows 8.1:

1. Open the Control Panel by pressing the Windows key + X on your keyboard and selecting “Control Panel” from the context menu.

2. In the Control Panel, click on “Uninstall a program” under the “Programs” category.

3. A list of installed programs will appear. Locate your third-party antivirus software in the list (e.g., Avast, Bitdefender, McAfee, etc.) and click on it to select it.

4. Click on the “Uninstall” button at the top of the list to start the uninstallation process.

5. Follow the on-screen prompts to complete the uninstallation. You may be asked to confirm the uninstallation or provide additional information.

6. Once the uninstallation is complete, restart your computer.

After restarting your computer, Windows Defender should be enabled and able to provide real-time protection against viruses, spyware, and other malicious software. If you encounter any issues during the uninstallation process or need further assistance, it is recommended to contact the customer service of the antivirus software provider for support.

Restart the Security Center Service

Security Center icon

1. Press the Windows key + R on your keyboard to open the Run dialog box.
2. Type services.msc in the Run dialog box and press Enter.
3. In the Services window that opens, scroll down and locate the Security Center service.
4. Right-click on the Security Center service and select Restart from the context menu.
5. Wait for the service to restart and then close the Services window.
6. Now, open the Control Panel by pressing the Windows key and searching for “Control Panel”.
7. In the Control Panel, click on System and Security.
8. Under the Security and Maintenance section, click on Action Center.
9. In the Action Center window, check if Windows Defender is now turned on. If not, click on the Turn on now button to enable it.

Repair System Files with SFC and DISM Commands

Repair tools or toolbox

To repair system files and resolve issues with Windows Defender in Windows 8.1, you can use the SFC (System File Checker) and DISM (Deployment Image Servicing and Management) commands. These commands can help fix corrupted or missing files that may be causing problems with Windows Defender.

Here’s how to use the SFC command:

1. Press the Windows key and X together to open the Quick Access menu.
2. Select “Command Prompt (Admin)” to open an elevated Command Prompt window.
3. In the Command Prompt window, type “sfc /scannow” and press Enter.
4. The SFC command will now scan your system for any corrupted files and attempt to repair them automatically.
5. Wait for the process to complete. This may take some time, so be patient.
6. Once the scan is finished, restart your computer and try turning on Windows Defender again.

If the SFC command doesn’t fix the issue, you can try the DISM command:

1. Open an elevated Command Prompt window as mentioned before.
2. In the Command Prompt window, type “dism /online /cleanup-image /restorehealth” and press Enter.
3. The DISM command will now scan your system and restore any corrupted files from your Windows installation media or Windows Update.
4. Again, wait for the process to complete and then restart your computer.
5. After the restart, check if you can turn on Windows Defender without any issues.

Using these commands can help resolve common issues with Windows Defender in Windows 8.1.

Modify Registry to Enable Defender

To modify the registry and enable Windows Defender in Windows 8.1, follow these steps:

1. Press the Windows key + R to open the Run dialog box.
2. Type “regedit” and press Enter to open the Windows Registry Editor.
3. In the Registry Editor, navigate to the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
4. If the Windows Defender key does not exist, right-click on the “Windows” key, select “New”, and then click on “Key”. Name the new key “Windows Defender”.
5. With the Windows Defender key selected, right-click on the right-hand side of the Registry Editor window and choose “New” > “DWORD (32-bit) Value”. Name the new value “DisableAntiSpyware”.
6. Double-click on the “DisableAntiSpyware” value and change the value data to “0”.
7. Click OK to save the changes.
8. Close the Registry Editor.

After modifying the registry, Windows Defender should now be enabled on your Windows 8.1 system.

Ensure System Is Up-to-Date

Windows update icon

To ensure that your Windows Defender is functioning properly on Windows 8.1, it is important to keep your system up-to-date. Regular system updates provide essential patches and security fixes that can help resolve issues with Windows Defender.

To update your system, follow these steps:

1. Press the Windows key and the “S” key simultaneously to open the search bar.
2. Type “Windows Update” and click on the “Windows Update settings” option.
3. In the Windows Update settings window, click on “Check for updates” to search for available updates.
4. If updates are found, click on “Install now” to start the update process.
5. Follow the on-screen instructions to complete the installation.

Updating your system can help ensure that Windows Defender is running with the latest security definitions and software updates, enhancing its ability to protect your computer against viruses, malware, and other threats.


Does Windows Defender still work on Windows 8?

Windows Defender may not be active on Windows 8 if a third-party antivirus program is installed.

Why can’t I activate Windows Defender?

You may not be able to activate Windows Defender due to Windows 10 updates, malware infections, or the presence of third-party antivirus software that could interfere with its operation.

How do I fix Windows Defender not turning on?

To fix Windows Defender not turning on, you can try the following solutions:

1. Uninstall any third-party antivirus software.
2. Restart the Security Center Service.
3. Run an SFC scan.
4. Install the latest updates for Windows.
5. Change your group policy settings.
6. Modify Windows Registry.
7. Perform a clean boot.

How to turn on Windows Defender in Windows 8?

To turn on Windows Defender in Windows 8, select the Start menu and type “group policy” in the search bar. Then, navigate to Computer Configuration > Administrative Templates > Windows Components > Microsoft Defender Antivirus.

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