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How to Fix Windows Defender Won’t Start

How to Fix Windows Defender Won’t Start

November 20, 2018 by Mitch Bartlett 4 Comments

Microsoft Windows 10 users may experience a common problem where Windows Defender won’t start on their system. The issue is often noticed when trying to turn Antivirus Protection on. Instead of the service turning on, the Windows\System32 folder will open.

The following fixes usually will fix this problem.

Fix 1 – Ensure Services are Started

  1. Hold the Windows Key and press “R” to bring up the Run box.
  2. Type “services.msc“, then press “Enter“.
  3. Select “Name” at the top of the row to sort by name, then scroll down to the entries that start with “Windows Defender“.
  4. Open anything that starts with “Windows Defender” and ensure the “Startup type” is set to “Automatic“. They should be listed as:
    • Windows Defender Advanced Threat Protection Service
    • Windows Defender Antivirus Network Inspection Service
    • Windows Defender Antivirus Service
    • Windows Defender Firewall
    • Windows Defender Security Center
  5. Restart the computer, then check to see if Windows Defender starts up.

Fix 2 – Registry Fix

  1. Login to the computer using an accoun that has Administrator rights.
  2. Hold the Windows Key and press “R” to bring up the Run box.
  3. Type “regedit“, then press “Enter“.
  4. The Registry Editor opens. Navigate to the following location in the registry:
    • HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows Defender
  5. Right-click the Windows Defender folder, then select “Permissions“.
  6. The Permissions window opens. Select the “Advanced” button.
  7. Select the “Change” link at the top of the window.
  8. In the “Enter the object name to select“, type “Administrators” then select “OK“.
  9. Check the “Replace owner on subcontainers and objects box” then select “Apply“.
  10. Double-click on the “Administrators” permission entry.
  11. Check the “Full Control” box, then select “OK“.
  12. Select “OK” again, then close the Registry Editor.
  13. Download the DefenderFix.zip file. This file contains information to fix a registry key.
  14. Open “DefenderFix.zip“, then open the “DefenderFix.reg” file.
  15. When prompted to import the changes, select “Yes“.
  16. Restart the computer, then check to see if Windows Defender starts up.

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Filed Under: Windows Tagged With: Windows 10

Reader Interactions

Comments

  1. Partha sarathi Mondal says

    March 21, 2021 at 8:53 am

    thanks. worked flawlessly.

  2. Bond says

    April 21, 2020 at 11:54 pm

    It’s showing cannot import

  3. Bear says

    February 1, 2020 at 7:30 pm

    woo hoo

  4. Bills says

    June 4, 2019 at 10:10 am

    Excellent and very good.

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Baby and Daddy My name is Mitch Bartlett. I've been working in technology for over 20 years in a wide range of tech jobs from Tech Support to Software Testing. I started this site as a technical guide for myself and it has grown into what I hope is a useful reference for all.

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