Why can't I turn on Windows Defender virus protection?
Today I noticed that my Windows Defender virus protection was off. I've been through countless blog entries, articles, and forums but I can't find anything that makes a difference.
I'm running Windows 10, Version 1803 (OS Build 17134.345)
I don't have any other antivirus software installed.
Here's the warning in Control Panel's Security and Maintenance section:
Clicking "Turn on now" brings up this blank Security Center window:
Under "Virus & threat protection", if I click "Scan now" nothing happens. If I click "Run a new advanced scan", then "Custom scan", then "Scan now" it'll prompt me to select a directory, but nothing happens after that.
Group Policy Editor
Computer Configuration > Administrative Templates > Windows Components > Windows Defender Antivirus
is still "Not configured"
Registry
HKLM/SOFTWARE/Microsoft/Windows Defender
-> DisableAntiSpyware
HKLM/SOFTWARE/Microsoft/Windows Defender
-> DisableAntiVirus
- both set to
0
Command Prompt
DISM.exe /Online /Cleanup-image /Restorehealth
didn't report any problemssfc /scannow
did find and repair corrupt system files, but after rebooting nothing has changed
Services
The "Restart" option for Security Center is disabled:
Update:
I went more than a week without a solution, but I was due for an upgrade anyway… New hard drive and fresh installation means the problem is gone even though it was never solved.
Unfortunately, I won't be able to test or accept an answer for this problem.
Best Answer
I had the same sort of symptoms. In the Windows Security Center, under Virus and threat protection, it said "Your virus & threat protection is managed by your organization."
I note you mentioned the Registry Keys under HKLM/SOFTWARE/Microsoft/Windows Defender. Nice spotting, but it seems like there is another key that is causing the problem for some users.
Steps to a solution:
Solution adapted from here, with a much more detailed solution here.