Windows Defender won't open? Here's how to fix it! (Windows 11)

Last edited: 23/4/2024

[PLEASE NOTE BEFORE READING]

This fix is more than 2 years old. There is a high likelihood that it may not work on your system.

BEFORE YOU COMMENT, "It doesn't work" or "Not working," PLEASE REMEMBER! There are actual users looking in the replies for other solutions as well. If it does not work for you, please also include the errors that you encountered and which step you got stuck on. This way also gives me a chance to possibly help you.

If you can't or do not want to include more information on not being able to proceed with this fix, simply move on and try other fixes.

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Remember: Make sure you are using an administrator account, are the owner of the device, or have permission from the administrator to proceed with these steps.

Windows 11 is a brand new OS. Windows Security may not be opening, as many users have said. The following steps may fix this issue for you:

Step 1: In search, type "PowerShell"

Step 2 As PowerShell appears, press "Run as Administrator" Click "Yes" on the following prompt.

Step 3: Enter the following commands separately in order shown.

1. Set-ExecutionPolicy Unrestricted

(If it prompts you with (Y/N) which is "Yes or No", type Y. If not, proceed to the next step)

2. Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”}

Added by mod (ty): Revert execution policy.

3. Set-ExecutionPolicy Restricted

Try opening Windows Security after. It should now work. Feel free to post any other solutions and questions.

EDIT:

This second option will work even if you are not an administrator:

https://techcommunity.microsoft.com/t5/windows-insider-program/issue-with-windows-defender-on-windows-11/m-p/3261866/highlight/true#M15320

Link suggested by hiThereSomeUserHere.

Suggested by Amirali Hendi:

Download the Windows Security App from the Microsoft website. The link: https://www.microsoft.com/en-us/microsoft-365/microsoft-defender-for-individuals

launch it and log in to your Microsoft account. Then close it. Now you can launch the Windows Security app!

(I am not a Microsoft official, so I cannot promise that this will not harm your computer. Make sure you have permission from the administrator before doing this.)

Hi, the first option with three steps gives me error. The error messages (long error messages) comes after I have entered the following command: Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”}

Then, I followed the second option, however the windows defender app does not allow me to sign in. What else can I try to fix the problem?

al hacer el paso 1 y poner "SI" me indica el siguiente comando.
Set-ExecutionPolicy : Windows PowerShell actualizó la directiva de ejecución correctamente, pero el valor queda

invalidado por una directiva definida en un ámbito más específico. Debido a esta invalidación, el shell mantendrá la

directiva de ejecución efectiva actual: RemoteSigned. Escriba "Get-ExecutionPolicy -List" para ver la configuración de

la directiva de ejecución. Para obtener más información, vea "Get-Help Set-ExecutionPolicy".

En línea: 1 Carácter: 1

• Set-ExecutionPolicy Unrestricted

• 
      + CategoryInfo          : PermissionDenied: (:) [Set-ExecutionPolicy], SecurityException 
  
      + FullyQualifiedErrorId : ExecutionPolicyOverride,Microsoft.PowerShell.Commands.SetExecutionPolicyCommand
  
  

la verdad no estoy seguro de que debo hacer, si me pudiesen ayudar.

PS C:\WINDOWS\system32> Set-ExecutionPolicy Unrestricted

Execution Policy Change

The execution policy helps protect you from scripts that you do not trust. Changing the execution policy might expose

you to the security risks described in the about_Execution_Policies help topic at

https:/go.microsoft.com/fwlink/?LinkID=135170. Do you want to change the execution policy?

[Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help (default is "N"): Y

PS C:\WINDOWS\system32> CategoryInfo : PermissionDenied: (:) [Set-ExecutionPolicy], SecurityException

: : The term ':' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the

spelling of the name, or if a path was included, verify that the path is correct and try again.

At line:1 char:35

• CategoryInfo : PermissionDenied: (:) [Set-ExecutionPolicy], SecurityE ...

•                               ~ 
  

  • CategoryInfo : ObjectNotFound: (::String) [], CommandNotFoundException
  • FullyQualifiedErrorId : CommandNotFoundException

PS C:\WINDOWS\system32>

It Didn't work

1st command run properly but 2nd didn't

2nd command gave errors

When I do this and I click open from the MS Store , I get the error alert that the path can't be found or I don't have necessary permissions. The app with the long name that refers to WIndows Defender is in the WindowsApps folder

I also get some errors when running the package commands , some of the errors are process in use

This was originally happening on boot