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Thread: Windows Defender Error 577 Cannot verify digital signal

  1. #1
    DianeDG is offline New Member
    Join Date
    Sep 2016

    Question Windows Defender Error 577 Cannot verify digital signal

    I recently uninstalled Webroot (chose not to renew); now I cannot get Windows Defender to run.

    When I try I get the following:

    Windows could not start the Windows Defender service on Local Computer. Error 577: Cannot verify digital signal; Recent hardware or software change might have installed a file incorrectly or damaged or might be malicious software source unknown.

    Don't know how to get Windows Defender to run. Any suggestions?

  2. #2
    HappyAndyK's Avatar
    HappyAndyK is offline Site Administrator
    Join Date
    Jun 2008


    If a security software leaves something behind, this can happen. So it is best to use AntiVirus Removal Tools & Uninstallers for AntiVirus programs

    Webroot may not have uninstalled fully and properly. Use this tool from Webroot to complete the uninstallation and see if it helps.

    See this post for more suggestions: Unable to turn on Windows Defender in Windows 7/8/10

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