π§ Step-by-Step Guide: Fix Windows Defender Not Working in Windows 11
Windows Defender (also known as Windows Security) is an essential built-in antivirus and security feature in Windows 11. If itβs not working as intended, your device could be exposed to serious vulnerabilities. Below, you’ll find detailed steps to diagnose and fix this issue.
π’ Step 1: Restart the Security Center Service
Sometimes Windows Defender won’t run correctly due to a Windows Security Center service interruption.
- Press
Win + R
keys together to open the Run dialog. -
Type:
services.msc
Press
Enter
. - Once the Services window opens, locate Security Center.
- Right-click it and select Restart or Start.
-
Next, double-click Security Center, set the Startup type to Automatic, and click OK.
-
Also find Windows Defender Antivirus Service, right-click, and select Restart or Start as needed.
- Afterward, restart your computer, then check if Windows Defender runs smoothly.
π’ Step 2: Use the Windows Defender Troubleshooter
Windows provides built-in troubleshooters that can quickly detect and fix problems.
- Open Settings (
Win
+I
). - Go to System β Troubleshoot β Other troubleshooters.
- Scroll down, then run the Windows Update troubleshooter as updates often resolve Defender issues.
- After completion, restart your PC and check your Windows Defender again.
π’ Step 3: Check and Install Windows Updates
Ensure Windows 11 is fully updated, as updates often include security patches.
- Go to Settings (
Win
+I
) β Windows Update. - Click Check for updates, install them if available.
- Reboot your system after installing all available updates.
π’ Step 4: Verify and Remove Other Third-party Antivirus Software
Windows Defender automatically disables itself if another antivirus is detected.
- Go to Settings β Apps β Installed apps.
- Search for third-party antivirus software (like Avast, AVG, McAfee, etc.).
- Click the three-dot icon next to the antivirus app and choose Uninstall.
- Restart the computer after completing the uninstallation to enable Windows Defender automatically.
π’ Step 5: Scan and Repair Windows System Files Using SFC and DISM
Corrupted files can cause Windows Defender to malfunction. Use SFC and DISM to repair corrupted system files.
- Press the
Win
key, type cmd, right-click on Command Prompt, and select Run as administrator.
Step A: Run System File Checker
bash
sfc /scannow
- Wait until the process completes 100%.
- If it finds corrupted files, it will auto-repair them.
Step B: Run DISM (Deployment Image Servicing and Management)
- Type each command below and press
Enter
after each:
bash
DISM /Online /Cleanup-Image /CheckHealth
DISM /Online /Cleanup-Image /ScanHealth
DISM /Online /Cleanup-Image /RestoreHealth
- Wait until each step completes and then restart your system.
π’ Step 6: Check Registry Settings (Advanced Users Only)
Misconfigurations in the registry can also cause Windows Defender issues.
- Press
Win + R
, typeregedit
and pressEnter
. - Navigate carefully to:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
-
Check for the registry entry named:
DisableAntiSpyware
- If you see it and it’s set to
1
, right-click β Modify and set it to0
. - Or delete the key entirely, letting Windows Defender handle defaults.
- Close Registry Editor and restart your computer.
β Warning: Editing the registry incorrectly could cause serious system issues. Always create a backup (File β Exportβ¦) before making registry changes.
π’ Step 7: Reset Windows Security App
If the issue still persists:
- Press
Win + I
to open Settings. - Select Apps β Installed apps.
- Search for Windows Security, click it, select Advanced options, and then click Reset.
- Restart your PC and see if Defender works normally.
π’ Step 8: Perform a Malicious Software Check with Microsoft Safety Scanner (Optional)
If you suspect infection has caused Windows Defender issues, scan your PC with Microsoft’s official Safety Scanner tool.
- Download from official link:
https://docs.microsoft.com/en-us/windows/security/threat-protection/intelligence/safety-scanner-download - Run the tool, execute a thorough scan, and let it repair any infections found.
π’ Step 9: Reset Windows 11 (Last Resort)
If all the above solutions fail, resetting your Windows installation might solve errors causing Windows Defender to malfunction.
- Backup your personal files first.
-
Navigate to:
Settings β System β Recovery
- Click on Reset PC.
- Choose:
- Keep my files (recommended)
- Or Remove everything (if severe problems exist).
- Follow the on-screen instructions to reset and repair your Windows installation.
π© Additional Tips:
- Regularly update your system.
- Avoid unnecessary registry modifications unless you fully understand consequences.
- Periodically perform full scans using Defender or reliable antivirus/malware tools.
π Conclusion
Following these detailed troubleshooting tips should resolve your Windows Defender issues on Windows 11. It’s important to have your built-in antivirus functioning effectively to keep your system secure and virus-free. If you still encounter issues, consider contacting Microsoft Support or visiting community forums for further assistance.