When opening Windows 11 Defender, it freezes on the screen with the Defender logo and closes after a couple of minutes.

Question

I performed a full system reset without saving files on disk, first using a local system image and then a cloud‑based one. After that, I tried to open Windows Defender, but it won’t open. A couple of months ago, before the reset, Windows Defender was working, and during this time I haven’t installed anything new on the PC. The latest possible updates have been installed, including optional ones. It's clean system Windows 11 ver.25H2 build 26200.8655.
I tried:

• Repair and reset via sistem components settings
• Restart the Windows Security Center Service
• Reinstall via C:\Windows\System32\SecurityHealth\10.0.29510.1001-0\Microsoft.SecHealthUI_8wekyb3d8bbwe.appx
• Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage
• DISM /Online /Cleanup-image /CheckhealthDISM /Online /Cleanup-image /Scanhealth
• DISM /Online /Cleanup-image /Restorehealth
• sfc /scannow
• DISM /Mount-Image /ImageFile:"G:\sources\install.wim" /Index:4 /MountDir:"C:\Temp" /ReadOnly
• DISM /Online /Cleanup-Image /RestoreHealth /Source:"C:\Temp\windows" /LimitAccess
• DISM /Unmount-Image /MountDir:"C:\Mount" /Discard

What should i do next? I really hope for your help.

Answer 1

Hello Evgenii,

Thank you for your detailed description. I can also see that you have already performed a number of troubleshooting steps.

May I ask if you have another Windows user profile on the PC?
If not, kindly create a new local administrator account and check whether Windows Defender opens correctly from the new profile.
You can use these steps through settings
https://support.microsoft.com/en-us/windows/manage-user-accounts-in-windows-104dc19f-6430-4b49-6a2b-e4dbd1dcdf32

To create a new user profile using Netplwiz
Press Windows + R, type netplwiz, and press Enter.

Click Add.

1. Select Sign in without a Microsoft account (not recommended).
2. Click Local account.
3. Enter a username and password, then click Next and Finish.
4. Back in the User Accounts window, select the newly created account and click Properties.
5. Open the Group Membership tab and select Administrator.
6. Click Apply and OK.
7. Sign out of your current account and sign in to the newly created account.
8. Try launching Windows Defender.

Kindly respond whether the issue persists in the new profile. This will help determine whether the issue is profile-specific or system-wide.

We look forward to your update so we can assist you further in resolving this issue.

Answer 2

It looks like I've managed to solve the problem.

I searched for a solution on YouTube and ran the following commands in Powershell as an administrator:

• Set-ExecutionPolicy Unrestricted
• Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage
• Get-AppxPackage -AllUsers | For each app: Add-AppxPackage -DisableDevelopmentMode -Register "$($_InstallLocation)\AppXManifest.xml

Windows Defender also didn't start.

After that, I decided to reinstall windows from the iso image I used for the DISM commands. I did a reinstallation with personal files preserved, and it worked!

There were some missing drivers and updates in the system after the installation, and I'm currently installing them.

Answer 3

Open Windows Powershell and copy/paste/run these commands:

gci 'C:\Windows\System32\SecurityHealth'-recurse -file -Include '*.dll', '*.exe', '*.appx'  | Get-AuthenticodeSignature | ft -auto Path, Status

reg query HKLM\System\CurrentControlSet\Services\SecurityHealthService /s

Expand the console screen so the output is visible and post a screenshot.