Windows Defender will not activate

  1. Posts : 10
    Windows 10 professinal

    Windows Defender will not activate

    Perhaps a year ago, a friend paid someone to provide a new computer. It is some HP model that came with Windows 8.1 pre-installed. It possibly also came from HP with one of the big name (Norton, McAfee, or whoever) "security scan" application installed. A freeware antivirus application (Avast), along with a few other freeware items, were added before it was delivered to him. His data collection was copied onto the new hard drive and various programs he already owned (e.g. Word) were installed.

    Today I offered to do the MS offered update to Windows 10 for him. Before beginning I uninstalled the security scan program and the Avast antivirus, wanting to just go with Windows Defender under Win10.

    After considerable hurry up and wait, Windows 10 Home was in place and running. My last effort was to be to assure that Windows Defender was running. It wasn't; it isn't.

    In Settings, on the Windows Defender tab, the controls are grayed out. At the very bottom is an active line saying something like
    Use windows Defender
    When I click on it I get a message box saying Windows Defender is inactivated. If I am using some other antivirus product, I should check its security settings. No other information is offered.

    There is not another program that I can find. Programs and Features on the Control Panel lists nothing that could have antivirus or other security functions. I suspect that some registry setting from one of the two now uninstalled programs caused Windows Defender to inactivate. A registry value to that effect was carried forward into the Widows 10 installation.

    Unfortunately I don't know how to go about finding this, nor what to do about it. Is there some turn-on-Defender override that is hidden outside the normal settings? How can I get Windows Defender to wake up and take notice?
    Last edited by AndyHw10f; 04 Oct 2015 at 03:09. Reason: to fix the title
      My Computer

  2. lx07's Avatar
    Posts : 5,479

    You could try the avast uninstaller from here to make sure it is fully uninstalled Avast FAQ | Avast 2015: Using the Uninstall Utility
      My Computer

  3. spapakons's Avatar
    Posts : 2,891
    Windows 10 Pro 64-bit 202H (Nov 2020 build 19042.867)

    Another option would be to reinstall Avast and uninstall it again. This would modify the registry automatically to enable Windows Defender when Avast is uninstalled. I think a better option to Windows Defender is Windows Security Essentials, but I don't know if there is a Windows 10 version yet or even if Windows Defender in Windows 10 is as good as Security Essentials so the latter isn't necessary.

    I read of how to disable Windows Defender. It involved a registry key, but I cannot find that right now. Search this forum to find the thread. Set the key as appropriate to enable it back.
      My Computer

  4. Ztruker's Avatar
    Posts : 13,512
    Windows 10 Pro X64 20H4 19042.746

    Microsoft Security Essentials (not Windows Security Essentials) will not run on Windows 8, 8.1 or 10 as the built-in Windows Defender is Microsoft Security Essentials as far as capability is concerned.
      My Computers

  5. spapakons's Avatar
    Posts : 2,891
    Windows 10 Pro 64-bit 202H (Nov 2020 build 19042.867)

    Yes, I thought so. Never tried installing it on Windows 8, I usually install another free antivirus such as Avast or AVG Free.
      My Computer


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