Unable to re-enable microsoft defender

Question

At some point Microsoft/Windows Defender was disabled on a PC I am supporting. Company policy has since dictated that it be active prior to being allowed to connect to the network due to a security issue being experienced by the company.

To date I've not been able to get Defender to start.

Starting the service also fails.

Answer 1

Hi Tony,

Issue reported: Unable to re-enable Windows Defender/Security.

Troubleshooting:

·         Run Command Prompt using admin rights

·         Enter this command and hit Enter

REG DELETE "HKLM\SOFTWARE\Policies\Microsoft\Windows Defender" /v DisableAntiSpyware

·         Once done restart your pc and try to turn on the Windows Defender again.

Please refer to the articles mentioned below for additional information.

Turn on Microsoft Defender Antivirus on enrolled device | Microsoft Learn

Use the command line to manage Microsoft Defender Antivirus | Microsoft Learn

Please update with your findings on this thread.

Thanks!

Answer 2

Thanks for the answer. Tried that and unfortunately nothing has changed.

Followed the steps in this guide you provided:

Turn on Microsoft Defender Antivirus on enrolled device | Microsoft Learn

Unfortunately when I go to the Virus and Threat protection page I have the following:

Clicking restart now results in an error after a while.

Manually attempting to start the Microsoft Defender service also results in an error:

Answer 3

If it's of assistance I can upload the support files generated from "getfiles" command?

Answer 4

Hi Tony,

Please follow an article mentioned below and update with your findings!

Troubleshoot Disappeared/Blank Windows Security in Windows 10/11 - Microsoft Community

If this article resolves your issues, please upvote an answer.

Thanks!