Windows 8 and 8.1 Forums


Failed Windows Defender definition update question

  1. #1

    Failed Windows Defender definition update question


    Hi All,
    Today I did a clean installation of Windows 8 and went straight to Windows Update to download all the updates. In total there were 116 to download, 115 for windows and 1 for Windows Defender. In windows Update history afterwards all were listed as succeeeded (installed correctly) except the Windows Defender definition which was listed as failed. The error code details shown for it was 80070666..but there was no information on what the code meant. The update was Windows Defender KB2267602 1.191.2648.0.
    To configure all the above updates obviously required a restart. After the restart Windows made no attempt to redownload the problematic Windows Defender Update. But a newer version KB2267602 1.191.2651.0. was listed along with 4 more Windows Updates so those were all downloaded and installed correctly including the newer Windows Defender definition. In Windows Update history all listed as succeeded. I checked the history again and the problematic Defender Update listed above (Windows Defender KB2267602 1.191.2648.0.) was still there showing as failed. Since then another 2 Window Defender definitions KB2267602 1.191.2655.0 and KB2267602 1.191.2687.0 have both been download and successfully installed.
    1.Has anybody any idea what might have happened here? Has the failed Windows Defender definition KB2267602 1.191.2648.0 been installed or not?
    2.Would an SFC Scannow have shown errors if there was a problem? I ran SFC Scannow and it came up fine..no errors.
    P.S Im sorry if the above explanation was a bit long winded!! I just wanted to try explain what happened correctly lol
    Thanks, Rick

      My System SpecsSystem Spec

  2. #2


    Harrisonburg, Va.
    Posts : 10,488
    Windows 8.1.1 Pro with Media Center


    Since you successfully installed 2 newer updates I wouldn't worry about the failed one.

    This might help---

    Windows Update error code 80070666 - Microsoft Community
      My System SpecsSystem Spec

  3. #3


    Do you think that because the initial defender update failed that the whole lot will have been downloaded again with the next definition update which successful. My only concern is if any of the definitions going back over the years have been missed i.e will the whole catalogue of updates have been installed? I wonder if Windows Defender recognises if any are missing and lets you know by failing to install the latest updates.

    if it
    Quote Originally Posted by David Bailey View Post
    Since you successfully installed 2 newer updates I wouldn't worry about the failed one.

    This might help---

    Windows Update error code 80070666 - Microsoft Community
      My System SpecsSystem Spec

  4. #4


    Harrisonburg, Va.
    Posts : 10,488
    Windows 8.1.1 Pro with Media Center


    If it was me I would click on Windows Update & see if it was offered again.

    I Have a bunch of failed updates & have later successful ones.

    Example---

    Click image for larger version

    I think I had to check for updates several times to get them to stick.
      My System SpecsSystem Spec

  5. #5


    HI David, Yeah Ive done that before myself but in this case it didn't offer it again. After the restart about five minutes after the initial Windows Defender definition failed (bearing in mind this was a clean installation) there was another Windows Defender definition offered and it was a newer version.

    Quote Originally Posted by David Bailey View Post
    If it was me I would click on Windows Update & see if it was offered again.

    I Have a bunch of failed updates & have later successful ones.

    Example---

    Click image for larger version

    I think I had to check for updates several times to get them to stick.
      My System SpecsSystem Spec

  6. #6


    Posts : 149
    Windows 7 Home Premium on 2 Windows 8.1 on 1


    I answered you on the MS forum. You seem concerned that you didn't get this specific definition update and that it wasn't offered again. The next definition (or the next) includes whatever was in the previous. As long as you have an up to date definition you are fine.
      My System SpecsSystem Spec

  7. #7


    Thanks Bru...yeah my definitions are up to date so it sounds like theres no problem

    Quote Originally Posted by bru View Post
    I answered you on the MS forum. You seem concerned that you didn't get this specific definition update and that it wasn't offered again. The next definition (or the next) includes whatever was in the previous. As long as you have an up to date definition you are fine.
      My System SpecsSystem Spec

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