how to fix windows defender service not started error
how to fix windows defender service not started error

how to fix windows defender service not started error


Hey readers! Are you struggling with the infamous "Windows Defender Service Not Started" error that hinders your PC’s security? We’ve got your back! In this comprehensive guide, we’ll delve into the causes and provide step-by-step solutions to help you fix this annoying issue. Let’s dive right in and restore your system’s protection!

Understanding the Error: Why is Windows Defender Service Not Starting?

The Windows Defender Service Not Started error occurs when a critical system service, responsible for scanning and protecting your PC against threats, fails to initialize. This can be caused by various factors, including corrupted system files, outdated software, or conflicts with other security applications.

Troubleshooting and Solutions

1. Check Windows Defender Service Settings

  • Open Services Utility: Press "Windows Key + R", type "services.msc," and hit "Enter."
  • Locate Windows Defender Service: Scroll down the list and find "Windows Defender Antivirus Service."
  • Verify Startup Type: Ensure it’s set to "Automatic" and check if it’s running. If not, right-click and select "Start."

2. Repair Corrupted System Files

  • Run System File Checker: Open the Command Prompt as administrator and type "sfc /scannow."
  • Let the Scan Complete: Wait for the scan to finish, and it will repair any corrupted system files.

3. Update Windows and Security Software

  • Check for Windows Updates: Go to "Settings > Update & Security > Windows Update" and install any available updates.
  • Update Security Software: Open Windows Defender and click "Update" to ensure you have the latest virus definitions.

4. Disable Third-Party Antivirus Programs

  • Uninstall Unnecessary Antivirus Software: If you have multiple antivirus programs installed, temporarily uninstall any that aren’t essential.
  • Check for Compatibility: Make sure your antivirus software is compatible with Windows Defender and disable any conflicting features.

5. Reset Windows Defender Settings

  • Open Group Policy Editor: Press "Windows Key + R," type "gpedit.msc," and hit "Enter."
  • Navigate to Windows Defender: Go to "Computer Configuration > Administrative Templates > Windows Components > Windows Defender Antivirus."
  • Disable and Re-enable Windows Defender: Double-click "Turn off Windows Defender Antivirus," set it to "Disabled," click "OK," then re-enable it.

Common Causes and Troubleshooting Table

Cause Troubleshooting Steps
Corrupted System Files Run System File Checker (SFC)
Outdated Software Update Windows and Security Software
Third-Party Antivirus Conflict Disable or Uninstall Conflicting Software
Misconfigured Group Policy Reset Windows Defender Settings in Group Policy Editor
Registry Corruption Use System Restore or Reinstall Windows


There you have it, readers! We’ve covered the various causes and solutions for the "Windows Defender Service Not Started" error. By following these steps, you can effectively fix this issue and ensure your PC remains protected against threats. If you encounter any further problems, don’t hesitate to check out our other articles for more troubleshooting tips. Remember, staying secure is essential for a smooth and protected PC experience.

FAQ about Windows Defender Service Not Started Error

1. What is the Windows Defender service?

Windows Defender is a built-in antivirus and antimalware software that protects your computer from threats.

2. What is the "Windows Defender service not started" error?

This error occurs when the Windows Defender service is not running and cannot be started.

3. What causes the "Windows Defender service not started" error?

This error can be caused by various factors, such as corrupted system files, malware infections, or software conflicts.

4. How can I fix the "Windows Defender service not started" error?

Follow these steps to troubleshoot the error:

5. Can I manually start the Windows Defender service?

Yes, you can manually start the service by:
– Opening the Command Prompt as administrator
– Typing "sc start windefend" and pressing Enter

6. What if manually starting the service doesn’t work?

If manual starting doesn’t work, try these advanced troubleshooting steps:
– Running the System File Checker (SFC) scan
– Performing a malware scan
– Resetting the Windows Defender service

7. Should I disable Windows Defender?

No, disabling Windows Defender is not recommended as it leaves your computer vulnerable to threats.

8. How can I prevent the "Windows Defender service not started" error from occurring again?

Regularly updating Windows and Windows Defender, keeping your antivirus software up-to-date, and avoiding suspicious software and websites can help prevent the error.

9. What other methods can I use to protect my computer?

In addition to Windows Defender, you can use other antimalware software, such as third-party antivirus programs or anti-spyware tools.

10. Where can I find more information about Windows Defender?

Microsoft provides extensive documentation on Windows Defender, which can be accessed through their official support website.