6 Methods to Fix Windows Defender won’t Turn On in Windows 10/11

If Windows Defender isn’t functioning, it is generally because it identifies another antimalware program. Make certain that the third-party security plan is entirely uninstalled using a specialized application. Check the system file with some of your operating system’s built-in command-line functions. To safeguard your PC, you should consider installing a full-fledged antivirus program.

Now, let’s look at the methods that may fix the Windows Defender won’t turn on the problem.


Reasons Why Won’t Windows Defender Turn On

a) Unable to activate Windows Defender:
This issue can also occur in Windows 8.1/10, but you should resolve it by utilizing one of our methods.

b) Windows Defender will not launch:
Many customers report that it will not launch on their PC. If this is the case, uninstall all third-party antivirus software from your computer. In addition, make careful to delete any antivirus-related files and registry keys.

c) Group Policy blocks Windows Defender:
Windows Defender will sometimes not run because Group Policy deactivates it. However, you can correct this by implementing one of our methods.

d) Windows Defender will not start due to an unexpected problem:
In some circumstances, you may receive an error message while launching this anti-virus product. If this occurs, run SFC and DISM scans to see if this resolves the problem.

e) After removing Avast, Bitdefender, McAfee, and AVG, Windows Defender would not start:
Even after uninstalling your antivirus, Windows Defender would occasionally fail to start. To resolve this issue, use the specialized removal program to delete any remaining files and registry entries related to your antivirus.

f) Windows Defender will not activate Windows 10 Spybot.
Many Windows 10 users have experienced this issue with the Spybot program. To resolve the issue, uninstall Spybot entirely from your computer and see if it fixes the problem.

g) Windows Defender will not open, operate, work, activate, or begin:
Several difficulties can arise, and if you are having trouble using Windows Defender on Windows 10 or Windows 11 computers, please check some of our alternatives.

6 Methods to Fix Windows Defender Won’t Turn On

Method 1: Run an SFC Scan

  1. To open Command Prompt as administrator, press Windows key + S, input cmd, and then click Run as administrator.
  2. Enter the following command and start preparing for the scan to execute: sfc /scannow

The System File Checker utility is used to fix corruption in the file system. Use this utility to determine whether or not Windows Defender is compromised. Follow the instructions above to run an SFC scan.

Don’t fret if the scannow command terminated before the procedure was completed; we have a simple solution for you.

If you cannot run an SFC scan or if SFC is unable to resolve the issue, you may choose to do a DISM scan instead. Proceed to the following step to do this.

Method 2: Run a DISM Scan

  1. As noted in the preceding step, launch Command Prompt as administrator.
  2. When Command Prompt appears, type and hit Enter to perform the following prompt: DISM /Online /Image Cleanup /RestoreHealth
  3. The DISM scan will now begin. This scan may take up to 20 mins or more, so please do not interrupt it.

Check to see whether the problem has been resolved after the scan. If you were unable to conduct an SFC scan previously, or if the DISM scan did not resolve your issue, run the SFC scan again and see if it fixes the problem.

If you’re experiencing difficulties using Command Prompt as an administrator, you should take a closer look at this useful tutorial to resolve the problem.

Method 3: Install a Better Antivirus

Windows Defender is a good security tool for your PC, but it falls short of the services and the functionality provided by a third-party antivirus.

If you use the Internet for shopping, finance, work, or entertainment, you should use a good antivirus, such as the one listed below, to safeguard your sensitive data.

This application is compatible with all major platforms, like Windows and Android and offers superior banking and privacy options. Over 110 million daily users recognize ESET’s multilayered security solution, so give it a go. Right now, you may take advantage of a 30-day trial period.

Method 4: Clean Boot Your Computer

1) Press Windows Key + R and type in msconfig. After that, press Enter or tap on OK.

2) The window System Configuration will now display. Now under the list check the Hide all Microsoft services box from the Services tab. Now, select the Disable all option.


3) Go to Startup and tap on Open Task Manager.

4) You will now see a list of starter apps. Disable the first entry on the list by right-clicking it. You should repeat this procedure for all starting apps except the known critical apps that should start during the system boot.


5) Return to the System Configuration window and hit Apply and OK once you’ve disabled all startup apps. Select to restart your computer now.

Third-party programs can sometimes interact with Windows and cause this issue to occur. Nevertheless, by doing a Clean Boot, you can locate the offending program.

Check to see whether the problem remains after restarting your computer. It implies that one of the deactivated applications or services was the source of the issue.

To locate the faulty app or service, you must activate them one by one or in groupings until the issue is reproduced. Now disable or remove the program, and it should address the problem.

Method 5: Use Antivirus Specific Removal Tools

When you remove third-party antivirus programs using the Control Panel’s Uninstall option, certain files may stay undetected, preventing you from using Windows Defender.

Some antivirus software has a dedicated removal program, which you may use to remove the antivirus quickly.

Perform a PC Scan with Restore Repair Tool to identify faults that are creating security issues and slowdowns. Following the completion of the scan, the repair procedure will install new files with new Windows files and bits.

You may also use an uninstaller program to uninstall your antivirus entirely from your computer. Uninstaller program, for those who are unfamiliar, is a specialised tool designed to remove applications.

The uninstaller will delete the selected software, but it will also delete all linked files and log files.

Consequently, the selected program will be entirely uninstalled, as if it had never been installed.

There are several excellent uninstaller programs available, but the finest is the one listed above. It’s extremely simple to use, so you should have no trouble removing your antivirus.

Method 6: Restart the Security Center Service

1) Press Windows key + R and launch Run

2) Type in services.msc and press Enter or tap on OK.

3) Look for the Security Center under Services. Select Restart from the menu that appears when you right-click on it.

4) Check to see if the issue with Windows Defender has been addressed after restarting the needed services.


We hope that these six troubleshooting methods helped you solve the Windows Defender won’t turn on issue. The most important method is to get a reliable and powerful antivirus that will help you protect your system from viruses, malware and other bugs.

Stefan Richard is one of the folks who can't have a life without technology, especially Microsoft products. He has more than 12+ experience in Information technology. He worked as IT trainer, network/system administrator and IT Infrastructure manager. Stefan is the co-founder of HecticGeek.

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