FIX: Service Couldn't be Started – Error 0x800106ba, in Windows Defender or Security Essentials (Solved)

This tutorial contains instructions to fix the error 0x800106ba in Microsoft Security Essentials or in Defender Antivirus: "The service couldn't be started. The program's service has stopped."

The Defender Antivirus & Security Essentials error 0x800106ba "Service Couldn't be Started", usually occurs when a third-party antivirus program is installed or because a malware program has disabled antivirus protection on your computer. To fix the error 0x800106ba follow the step below.


FIX: Error Code 0x800106ba - Security Essentials or Defender Antivirus Service Couldn't be Started

Attention: If you receive the Security Essentials error 0x800106ba, after installing a third party antivirus, this is normal. At this case, you have to uninstall the third-party antivirus to fix the problem.

Method 1. Turn on the Real Time Protection Manually.

In some cases the error 0x800106ba in Security Essentials & Defender Antivirus can be easily resolved by activating the real-time protection. So, click the Turn on button and wait to see if the problem is resolved. If after 1-2 minutes, the problem remains, to the next method.

Security Essentials Real Time protection is Off

Method 2. Scan your computer for Malware & Viruses.

The next method to fix the error "The service couldn't be started" in Defender Antivirus (or in Security Essentials AV), is to scan and clean your system from viruses and malware. For that task follow the instructions in this guide: How To Scan Your Computer for Viruses and other Malicious Programs.


Method 3. Enable the Windows Defender Service in Registry.

1. Open the Registry Editor. To do that:

1. Press Windows image + R keys to open the run command box.
2. Type regedit  and press Enter.

registry editor


3. In Windows registry editor locate the following key:

  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WinDefend

4. At the right pane, double click at the Start value and set the value data from 4 to 2.
5. When done, click OK.


6. Close the registry editor and restart your PC.
7. If after restart the problem persists continue to next method.

Method 4. Turn On the Real Time Protection from Registry.

1. Open the Registry Editor.
2. Navigate to the following key at the left pane:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender

3. Right click at the Windows Defender key and click Permissions.


disable windows defender

4. Click Advanced and then click Change owner.

disable windows defender windows 8


5. At "Enter the name to select" box, type Administrators and click OK.

turn off windows defender windows 10



6. Click Replace owner on subcontainers and objects and click Apply.

disable defender antivirus windows 10


7. Double click at Administrators entry.

disable defender security windows 10


8. Check the Full Control check box and then click OK three (3) times to close permission properties.

disable defender security


9. Close Registry Editor.

10. Re-open Registry Editor and navigate to the same registry location:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender

11. At the right pane, double click to open the DisableAntiSpyware REG_DWORD value and change the value data to 0

Enable Windows Defender registry


12. Then open the DisableAntiVirus REG_DWORD value and change the value data to 0. *

* Note: If you own Windows 7 OS, skip this and the next step, close the registry editor and restart your PC.

13. Finally, navigate to this key:

  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SecurityHealthService

14. At the right pane double click at Start REG_DWORD value and change the value data to 3.

Enable Defender Antivirus in Registry

15. Close Registry Editor and restart your computer.

That's all folks! Did it work for you?
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