Windows Security on Windows 11 Not Working Problem Fixed

How to fix Windows Security on Windows 11 not working quickly? Windows Security is vital to the security of your PC, so you need to follow the fixes below to get it back to normal as soon as possible.


By Maggie Updated on December 1, 2023

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What Causes Windows Defender Not Working on Windows 11

Windows Security is the free and default antivirus program provided by Microsoft to protect your PC from external threats. Windows Defender is known as Microsoft Defender in Windows 11, and it is managed through Windows Security. However, sometimes this security software may stop working or in some cases it may not start at all.

Windows 11 Logo

Before you can start solving this problem, you need to understand what is causing this error. The following are possible reasons why the Windows 11 Windows Defender not working:

🛒 Corrupted Windows security components - If you recently upgraded to Windows 11 from an older version of Windows, you may be dealing with some corrupted components caused by the upgrade process. To resolve this issue, you will need to reinstall the Windows security components.
🎳 System file corruption - You cannot open Windows security components or your Windows 11 Windows Defender not work due to corrupted system files that directly affect Windows security or related dependencies. To resolve this issue, you can first perform an SFC and DISM scan.
🎪 Windows Security is Disabled - If you have previously made some changes to the default behavior of Windows Security, Windows Security may actually be disabled by a registry entry, which is why it doesn't work or you can't access it.

Now that we understand all the potential scenarios that could cause Windows Security to not work or not open on Windows 11, let us know about all the known fixes that other affected users have successfully used to restore normal functionality to Windows Security Center.

Provide Protection for Your Important Files on Windows 11

If your Windows Security on Windows 11 is not working, you must be desperate to get it back to normal and then provide protection for your computer. Not fixing it in time could expose your computer to malware or viruses.

Before you take the following solution measures, we recommend that you make a backup of the important files on your computer. Because you can't predict what will happen during the repair process, in order to avoid you to experience the pain of data loss. Backing up in advance is the wisest choice.

AOMEI Backupper Standard is a backup and recovery software designed for all Windows PCs, including Windows 11/10/8.1/8/7/Vista/XP. It also allows you to create bootable media to restore your data and system if your computer does not boot properly. You can refer to the following steps to use this free software to backup your important files on Windows 11.

Download FreewareWin 11/10/8.1/8/7/XP
Secure Download
  1. Launch AOMEI Backupper Standard, you will see its deep-blue interface. Then, click File Backup under the Backup tab.

File Backup

  1. Click Add File or Add Folder according to your needs. Choose the files or folders which you want to backup.

Add File or Add Folder

  1. Click the second box to select backup destination. You can backup files to external hard drive, NAS network location, or other locations as long as it can be detected by Windows.

Select Destination

  1. Confirm everything is OK and click Start Backup to backup files.

Start Backup

🎉 Tips:
☻ Schedule Backup: you can click Schedule to automate the file backup task. You can schedule backup in daily/weekly/monthly mode. There are two advanced schedule modes, event triggers and USB plug in, which are only available in AOMEI Backupper Professional and higher editions. 
 Backup Options: you can comment, enable email notification, set compression level, create pre/post-command, etc. 
☻ Backup Scheme: 4 different backup schemes are supported and you can use them to delete old backups to free up disk space while keeping the latest backup versions. But they are available on AOMEI Backupper Professional at least.

How to Fix Windows Security in Windows 11 Not Working or Opening

Here is a list of solutions you can try to make Windows Security work again in Windows 11. You can try each of them:

#1. Reinstall Windows Security using PowerShell Command

This issue with Windows Security not working on Windows 11 is not new, and has been reported by Windows 10 users when upgrading from feature updates. Windows Defender (aka Microsoft Defender) isn't installed on your computer like a regular program, so you can't reinstall it like regular software. Instead, follow these instructions and use the PowerShell command to learn how to reinstall Windows Security on Windows 11.

  1. Right-click on the Start menu and select Windows Terminal (Admin). This will open Windows PowerShell in admin mode.

Windows Terminal

  1. Now, run the following commands one by one in the terminal and hit Enter after each command.
  • Set-ExecutionPolicy Unrestricted
  • Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}


  1. Once you see the success message, close PowerShell and restart your computer. This will disable development mode for all applications. Now, try opening the Windows Security application and it should work fine.

#2. Reset Windows Security App

When your Windows Security for Windows 11 not working or not opening, you can choose to reset this software. Resetting will clear all settings for this application and start again as if you had just installed Windows Defender.

  1. Press Windows + I to open Settings and navigate to Apps -> Apps & features.
  2. Search for Windows Security in the search box of the Applications list.
  3. Click on the three-dot vertical menu and open Advanced Options.
  4. Find the Reset section and click the Reset button.

Reset Windows Security

  1. Once done, open Windows Security and it should work as expected.

#3. Run DISM and SFC Command

The System File Checker and DISM commands can help to replace corrupted files with new ones. So when applications like Windows Security are not working or not opening, you can try running these two commands to see if you can get help.

  1. Press Windows + R to open the Run dialog box, type cmd and hit Ctrl + Shift + Enter together (instead of pressing enter) to open an elevated Command Prompt.
  2. Once you’re in Command Prompt, paste the below code and hit Enter:
  • DISM /Online /Cleanup-Image /RestoreHealth

DISM Command

  1. After completing this step, keep the Command Prompt window open to run the SFC command. Paste the below code in the Command Prompt window, and hit Enter.
  • sfc /scannow

SFC Command

#4. Reset Your PC

Resetting your computer settings is a panacea for almost all Windows errors, it resets your computer back to its initial state. This is much better than reinstalling the entire Windows because you can reset your computer while keeping your personal files and folders intact.

  1. Press Windows + I to open Settings.
  2. Go to System -> Recovery. Click on Reset PC under Recovery options.

Reset PC

  1. Click on Keep my files.

Keep My Files

Follow the instructions and you will be able to reset your PC. After resetting your PC, you must set up Windows 11. When finished, check to see if the “Windows 11 Windows Defender not working” error has been fixed.


After reading this article, the problem of "Windows Security on Windows 11 not working " should be solved. But you can't take the security of your data and system lightly. Many users are also experiencing problems with the Start Menu not working on Windows 11. As long as you use AOMEI Backupper to backup your computer, you never have to worry about data loss or system crash. Download and try it now.

Maggie · Editor
Maggie is a technical editor from AOMEI and troubleshoots technical problems against data protection. She has received professional and systematic technical training. With a focus on user experience, security, and problem-solving, she always puts herself in the readers' shoes and provides them with valuable technical insights.