Error 0x800106a, Windows Defender will not turn on

Windows Defender is one of the best free antivirus software for Windows 10 / 8. Since it is easy and reliable to use, most of the users prefer to use it. Today, we came around an error faced on Windows Defender while turning it on. One of my readers reported that when he turns on the Windows Defender, he is unable to do so.

He has sent us the error screenshot:


When he tried to turn on Windows Defender, its icon turned red with above-shown message. AlsoDefender showed that the version is outdated. After doing some research, I came around to this thread and found the fix.

Error 0x800106a, Unable To Turn On Windows Defender

Way  – 1 : Verify whether Windows Defender service is running or not

1. Press Windows Key + R combination, type put services.msc in Run dialog box and hit Enter to open the Services.

2. Scroll down to look for Windows Defender Service and double click on it to modify its status:


3. In the following window, make sure that service is running. If you’re facing the issue then this service may be showing stopped status. Click on Start and pick Startup type to Automatic. Click Apply followed by OK.


4. Reboot the system once, this may be helpful and the issue should be resolved by restarting the computer.

Way  – 2 : Fix using Command Prompt

1. Open administrative Command Prompt, type following commands one by one followed by Enter key:

  • regsvr32  atl.dll
  • regsvr32  wuapi.dll
  • regsvr32  softpub.dll
  • regsvr32  mssip32.dll


2. Now close the Command Prompt and reboot the system. The issue should be fixed out significantly.

Hope this helps!

These posts Windows Defender is not working or Unable to turn on Windows Defender may also help you.

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An Electrical Engineer by profession, Kapil is a Microsoft MVP and a Microsoft Content Creator. Please read the entire post & the comments first & create a system restore point before making any changes to your system.