Build 9860 Warning: Windows Defender won't run

After installing the latest build, I got a security notice.  Looking into it, I found Windows Defender was not running.

I check 'windows update' and there were 2 'important' updates.

I applied both and now Windows Defender is running.

Perhaps there should be a warning to others about this minor problem.

Other than that, I like this new build so far.


Question Info

Last updated May 16, 2018 Views 463 Applies to:


Welcome to Microsoft Community.
1. Do you get any error message?
2. Do you have any third party antivirus program installed on your computer?

Windows Defender is included with Windows and helps protect your PC against malware (malicious software). Malware consists of viruses, spyware, and other potentially unwanted software. Malware can infect your PC without your knowledge: it might install itself from an email message, when you connect to the Internet, or when you install certain apps using a USB flash drive, CD, DVD, or other removable media. Some malware can also be programmed to run at unexpected times, not only when it's installed. If you have any third party antivirus program installed on your computer, then you will not be able to use Windows defender as you will have conflict.

I would suggest you to try the following methods and let’s know the results.

Method 1: Start the Windows Defender Service Manually

 a)       Press “Windows Logo” + “R” keys on the keyboard to open the “Run” command box.
b)       Type “Services.msc” in the “Run” command box and press “Enter”.
c)       In the “Services” window, search for the “Windows Defender” service from that list.
d)       Double-click on it to open its “Properties” window.
e)       From its “Properties” window, click on “Start” when the service is stopped and also change its “Startup Type” to “Automatic”.
f)        Click on “Apply” and “Ok”.
g)       Restart the computer and check if that resolves the issue.

If the issue still persists, then try the next method.

Method 2: Run Windows Defender as Administrator
a)       From the Windows 8 Start Screen, type “Defender”. Windows Defender should appear in the list.
b)       Right click on the “Windows Defender” icon and select “Run as Administrator” from that menu.
c)       Check if that launches Windows Defender on the computer and check if you are able to turn it ON.

Post us the results after you try the above steps.

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