Is Windows Defender not working, refusing to turn on or showing errors? Is your real-time protection disabled? Follow these 6 tested solutions to restore your Windows antivirus and secure your PC right away.
Diagnosing the Windows Defender problem
Windows Defender (now Microsoft Defender) can malfunction for several reasons: a conflict with another antivirus, corrupted Windows services, malware deliberately blocking protection or a faulty Windows update.
Common symptoms include a red security icon in the taskbar, the message “Real-time protection is off”, being unable to turn on Windows Defender manually, or scans that will not start.
First check whether a third-party antivirus (Avast, Norton, McAfee) is installed. Windows automatically disables Defender when it detects another security solution, to avoid system conflicts.
The Windows Security app (shield icon in the taskbar) shows the detailed status of your protection and pinpoints which components are failing.
Fix 1: Restart the Windows Defender services
Open Windows Services: Windows key + R → type “services.msc” → Enter. Find these critical services: “Microsoft Defender Antivirus Service”, “Windows Defender Firewall” and “Microsoft Defender Antivirus Network Inspection Service”.
Restart each service: right-click → “Restart” (or “Start” if it is stopped). Set the startup type to “Automatic” to avoid future failures.
Restart your PC after the change. This fixes 70% of Defender problems according to Microsoft support statistics.
Fix 2: Use the built-in troubleshooter
Windows 10/11 includes an automatic troubleshooter for Windows Defender. Settings → Update & Security → Troubleshoot → Additional troubleshooters → “Windows Security”.
Run the troubleshooter and let Windows diagnose the problems automatically. The tool repairs corrupted registry entries, restores default settings and restarts blocked services.
Quick alternative: Settings → Privacy & security → Windows Security → Virus & threat protection → “Scan options”.
Fix 3: Remove competing antivirus software
Completely uninstall any third-party antivirus via Control Panel → Programs and Features. Be careful: some leave traces behind that still block Defender.
Use the vendors’ official removal tools: Avast Uninstall Utility, Norton Remove and Reinstall Tool, McAfee Removal Tool. These utilities clean up hidden files and registry entries.
Restart and check that Windows Defender turns on automatically. If the problem persists, an extra restart is sometimes needed for full detection.
Fix 4: Reset the security settings
Open PowerShell as administrator (right-click the Start menu → “Windows PowerShell (Admin)”). Run this command: Get-AppXPackage -AllUsers -Name Microsoft.SecHealthUI | Reset-AppxPackage
This command resets the Windows Security app without affecting your other data. Wait a few minutes for the automatic reinstallation.
Graphical alternative: Settings → Apps → Apps & features → “Windows Security” → Advanced options → “Reset”.
Fix 5: Check Group Policy
Windows Pro/Enterprise only: Windows key + R → “gpedit.msc” → Computer Configuration → Administrative Templates → Windows Components → Microsoft Defender Antivirus.
Check that “Turn off Microsoft Defender Antivirus” is set to “Not Configured” or “Disabled”. If it is enabled, double-click → “Disabled” → Apply.
Run gpupdate /force from the command line to apply the policy changes immediately without waiting for automatic synchronisation.
Fix 6: Advanced system repair
If none of the solutions work, run SFC and DISM to repair corrupted Windows system files. Open cmd as administrator:
sfc /scannow(checks and repairs system files)DISM /Online /Cleanup-Image /RestoreHealth(repairs the Windows image)- Restart after each command
These Microsoft tools restore Defender components damaged by malware or faulty installations.
Windows Defender not working: temporary protection
Use Microsoft Safety Scanner or Malwarebytes for temporary protection while you repair Defender. Never leave your PC without active antivirus protection.
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