1. Uninstall Third-Party Antivirus Software
Conflicts are a frequent cause of this error.
- Go to Control Panel → Programs and Features
- Remove any third-party antivirus tools
- Restart your PC
2. Reinstall Microsoft Defender for Endpoint (if applicable)
- Uninstall the existing Defender for Endpoint client
- Download the latest version from Microsoft’s official site
- Perform a clean reinstallation
3. Run the Windows Activation Troubleshooter
- Open Settings → Update & Security → Activation
- Click Troubleshoot
- Follow the on-screen instructions to resolve activation issues
4. Update Windows to the Latest Version
- Go to Settings → Update & Security → Windows Update
- Install all available updates
- Restart after the update completes
5. Perform System File Check and Health Restore
- Open Command Prompt (Admin)
sfc /scannow
DISM /Online /Cleanup-Image /RestoreHealth
- Restart your system after both scans
6. Reset Microsoft Store Licensing (if applicable)
- Open PowerShell as Administrator
- wsreset.exe
This resets Microsoft Store and clears licensing cache issues.
7. Reset Windows Licensing State (Advanced)
- Open Command Prompt (Admin)
Run:
slmgr.vbs /dlv
slmgr.vbs /rearm
- Restart your system to apply the changes
8. Check Group Policy for Defender Blocking
- Press Win + R, type gpedit.msc, and press Enter
- Navigate to:
- Computer Configuration → Administrative Templates → Windows Components → Microsoft Defender Antivirus
- Ensure that "Turn off Microsoft Defender Antivirus" is set to Not Configured or Disabled
9. Verify and Clean Defender Registry Keys (Advanced Users)
- Open Registry Editor (type regedit)
- Go to:
- HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
- Carefully remove any restrictive keys or policies
10. Contact Microsoft Support (Enterprise or Persistent Issues)
If none of the above resolves the error:
- Reach out to your IT administrator (for enterprise users)
Or contact Microsoft Support directly for licensing validation or Defender troubleshooting