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Windows Defender is the first line of defense for your Windows computer. That’s why, you and almost every other Windows user prefers enabling the Windows Defender at all times.

When you turn on Windows Defender, you feel that your computer is more secure; even more than enabling any antivirus software.

The real-time protection offered by Windows Defender keeps common malwares and viruses at bay. You are stress-free because you know that this program is protecting your PC and rebuffing anything that tries to harm it.

Likewise, you start to panic when the Windows Defender won’t turn on in Windows 10. And, you should. There are many reasons why a disabled Windows Defender should scare you.

Before you look into different ways to turn on Windows Defender, check out the reasons why shouldn’t turn off Windows Defender on your Windows 10/8/7 computer.

What Happens When Windows Defender Won’t Turn On in Windows 10?

Being a built-in antivirus, Windows Defender is supposed to stay enabled at all times. On Windows 10, you can turn it on by going to the Update & Security section in the Settings menu.

However, you are unable to turn Windows Defender on due to a few interferences. Existing antivirus software may disable it or your Windows Registry wasn’t allowing the permission to run it.

Regardless of these reasons, you should know that a disabled Windows Defender puts your PC at a great risk of being attacked by virus, malware and other dangers.

Here’s a list of what happens when Windows Defender won’t turn on in Windows 10 –

  • Your system’s boot time slows down
  • You are unable to run Windows Updates
  • The option of Controlled Folder Access goes out the window
  • Your PC doesn’t get an advanced level of protection
  • Malware protection of other third-party software gets downgraded (false positives rate increases)
  • Windows operating system is unable to integrate malware protection with its Security Center

Keeping the Windows Defender is, therefore, essential. And, when you can’t turn it on in the normal manner, there are a few ways that make it possible.

1. Reboot the Security Center

Reboot the Security Center

In Windows 10/8/7, the Windows Defender is integrated with the Microsoft Security Center service. If the Windows Defender is not working properly, you can restart the Security Center.

This enables the Windows Defender whenever you log on to your computer.

  • Open the Run dialog box by pressing ‘Windows’ key and ‘R’ key
  • Type ‘services.msc’  in the Open dialog box
  • Press the Enter key or click on the OK button
  • Check for ‘Security Center’ in the list of services
  • Right-click on Security Center
  • Click on Restart

After you reboot the Windows Security Center service, restart your computer. Turn on the Windows Defender in the usual manner by going to the Update & Security section in the Settings app. See if this fixes the problem.


Clean Boot your PC

Clean Boot your PC

It is a great solution to reboot your computer back to normal. A clean boot can restore your computer settings to default and allow you to enable Windows Defender properly.

You need to log on to your Windows with the administrator account. To clean boot Windows 10, follow these steps.

  • Go to Start menu
  • Search for ‘msconfig’ and click on System Configuration app
  • Go to the Services tab
  • Check the box for ‘Hide all Microsoft services
  • Click on ‘Disable all
  • Now, go to the ‘Startup’ tab
  • Click on ‘Open Task Manager
  • Select the enabled items and disable them by right-clicking on each of them
  • Close the Task Manager
  • Click on OK
  • Restart the computer

2. Use the Local Group Policy Editor

Use the Local Group Policy Editor

In some cases, Windows Defender won’t open if your group policy has disabled it. You need to edit the Local Group Policy of your Windows computer to fix this issue.

To change your group policy,

  • Launch the Run application (press ‘Windows’ and ‘R’ key)
  • Type ‘gpedit.msc’  in the Open dialog box
  • Click on OK or press the Enter key
  • This opens the Group Policy Editor window
  • In the left pane, navigate to Computer Configuration
  • Go to ‘Administrative Template
  • Click on ‘Windows Components
  • Go to ‘Windows Defender Antivirus
  • Go to the right pane
  • Double-click on – ‘Turn off Windows Defender’
  • Select the option – Not Configured
  • Click on Apply and then on OK to save changes

This method enables Windows Defender only when it is disabled by the Group Policy editor.

3. Adjust Your Registry

Similarly, your Windows Registry can also disable Windows Defender. To fix the issue, you need to modify the registry so it doesn’t interfere with Windows Defender.

  • Launch the Run application (press ‘Windows’ and ‘R’ key)
  • Type ‘regedit’ in the dialog box and press the Enter key
  • After the Registry Editor opens, go to the left pane and navigate to the following address – HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
  • Now, in the right pane, search for ‘DisableAntiSpyware DWORD
  • Double-click on it

If you can’t detect the DWORD,

  • Right-click on the right plane
  • Choose ‘New’ and select DWORD (32-bit) Value
  • Set the Value to 0 and click on OK to save changes

If you prefer an advanced and faster way to modify the registry, follow these steps:

Adjust Your Registry

  • Go to the Start menu
  • Search for ‘command prompt’ and press the Enter key
  • Right-click on Command Prompt and click on ‘Run as Administrator
  • Enter the following command
REG ADD “HKLM\SOFTWARE\Policies\Microsoft\Windows Defender” /v DisableAntiSpyware /t REG_DWORD /d 0 /f
  • Press the Enter key to run it

This method instantly changes the DWORD value to 0 and your issue gets resolved in a jiffy.

4. Use Specific Antivirus Removal Tools

In many cases, third-party antivirus can interfere with Windows Defender. They can disable the Defender and prevent it to run malware protection. This protocol allows the antivirus software to run properly.

You can uninstall such software to permanently stop it from interfering with Windows Defender. Or, you can use antivirus removal tools.

You can view the list of trusted antivirus removal tools (recommended by Microsoft) in the link below.


Run an SFC scan

Sometimes, corrupted system files can also disable Windows Defender. In such cases, you can scan your PC with the System File Checker (SFC) program. To run an SFC scan,

  • Type ‘cmd’ in the Windows 10 search box
  • Go to Command Prompt program from the search results
  • Right-click on it and select ‘Run as administrator’ from the context menu
  • Type the command ‘sfc /scannow’ in the Command Prompt window
  • Press the Enter key to execute the scan
  • Wait for the scan to finish (this make take a couple of minutes)
  • Restart your PC

The scan fixes the corrupted files automatically. After restarting, you can check if you are able to enable Windows Defender properly or not.


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