Windows Security Dashboard issue: "You'll need a new app to open this windowsdefender link"

Any 3rd party anti virus, security, cleanup programs EVER installed on the computer?

Hello alext92,welcome to the Microsoft community, my name is Luiz Cruz, an independent consultant and I would be happy to help you.

First I recommend that you try the following:

Press Windows key + I and access the settings;
Click Applications;
In "Choose where to download applications from" change the option to "From anywhere";

Try opening Windows security again, if you still can't, try the instructions below:

Click on the Start Menu and type PowerShell and select to open as an administrator;
Copy and paste the following command:
Add-AppxPackage -Register -DisableDevelopmentMode "C:\Windows\SystemApps\Microsoft.Windows.SecHealthUI_cw5n1h2txyewy\AppXManifest.xml"

Now check if the problem has been fixed;

I hope I helped, see you soon!

I had Ccleaner some years ago, beside that never installed antivirus or other cleaner programs

Hello, thank you for the response.

The option to "download from anywhere" was already selected. 

About the other solution I get this error message in powershell:

"Add- AppxPackage: The 'Add- AppxPackage' command was found in the module 'Appx', but the module could not be loaded. For more information, run 'Import-Module Appx'."

PS: if then I run "Import-Module Appx" I get another error: "Import-Module: Operation is not supported on this platform. (0x80131539)"

Hello,

Try these steps:

1. Open Windows PowerShell.

2. Execute this command:

Get-AppxPackage *Microsoft.Windows.SecHealthUI* | Reset-AppxPackage

Let the command complete.

See if this resolves the issue.

Reference: https://www.kapilarya.com/fix-microsoft-defender-not-working-in-windows-10

Hope this helps!

Note: Included link in this reply refers to blog post by a trusted Microsoft MVP.

Hello,

thanks for the advice, the command was executed but seems that nothing changed...

Dear alext92,do you have any non-Microsoft anti-virus installed? If so, I recommend that you temporarily uninstall it for testing;

Check for new updates on Windows Update:

1: Open the Windows 10 "Start" menu and select the "Settings" item.
2: then select the "Update and Security" option.
3: in the "Windows Update" section, click "Check for updates".
4: If there are no updates, the message "You are up to date" will be displayed.
5: if there is any pending system update, the message "Features update for Windows 10 ..." will be displayed, then click on the "Download and install" item to start the system update.
6: wait for the update download to finish and restart the PC, or schedule a restart to be able to finish the procedure.

Make a clean boot:

Clean boot serves to determine whether a background program is interfering with the system or optimizing system loading.

1. Press the Windows + R keys, type msconfig and click OK;
2. In the System Configuration window, click on the services tab;
3. At the bottom of the screen, check the Hide all Microsoft services box and click Disable all;
4. Now click on the Programs Startup tab and on Open Task Manager;
5. When loading the task manager, click on the start tab and disable all non-Microsoft programs (right-click on the program and choose disable), close the Task Manager and click OK on system configuration and restart computer if requested.

NOTE: This procedure disables all third party services and programs. You can later, if the problem is solved in this way, selectively enable the programs and services that will start with Windows, instead of keeping all disabled. If the problem returns after activating the startup of a specific service or program, the problem is exactly in the startup of this software and it is recommended to remove it.

Restart the pc and try to open Defender again, if the problem still persists, try to execute the command sent in the previous post in PowerShell;

I hope this helps, see you soon!

Hi, I am on the latest build, so no updates available. Unfortunately clean booting windows didn't work

Dear alext92,in that case I recommend that you try:

Press the keys Ctrl + Shift + ESC, click on File;
Click Run new task.
Check the option Create this task with administrative privileges;
In the open field type cmd, then click OK.
Run the following commands:

sfc /scannow
dism /online /cleanup-image /CheckHealth
dism /online /cleanup-image /restorehealth
chkdsk /f /r /b


Confirm with Y and then Enter to schedule a disk scan. Restart the equipment and as soon as you finish, check if you agree.

Wait for the process to finish and restart the pc;

Check if the problem has been corrected;

I hope I helped, even more!

All those checks went fine, but didn't work... I will wait for the next windows update and see if that fixes my problem