The KB5079473 security update caused my laptop to simply stop working.

I can't access Outlook, I can't access my C drive, it says I'm not the administrator of my laptop (even though I am), I can't take screenshots or open any Office documents. It's a disgrace! I work with my laptop and now I can't do anything because of this disastrous update.

I too am unable to use my laptop since the Windows KB5079473 security updated was made this morning! I can't run troubleshooting or even Windows+R. My C drive is missing too.

I have the same problem... Also My administrator account can't rollback the update.

My laptop is useless!

I'll try restore windows from USB drive. In other PC i'm downloading the installation iso.

Even from winre can't restore or delete the update. Some folders are accesible, but any workaround is useless

I just make it work.

From administrator user, I uninstalled one update, then I properties from the disk, under security tab, I add all the users missing.

When I apply, shows an error, but when I restart everything work as usual

Same thing here. I can't access administrator privileges or C drive, can't uninstal the KB5079473. Can't take screenshots or use Office.

Even i am not able to access the C drive

Do you have a Samsung device?

Ive just found in the Windows release health dashboard, that known issues have been reported for the Windows 11, version 25H2 update with loss of access to C: drive and App failures for some Samsung devices in specific regions after installing KB5077181.

Microsoft and Samsung investigated these reports and concluded that the symptoms were caused by an issue in the Samsung Galaxy Connect app. While the reports coincided with recent March Patch Tuesday timing, investigation confirmed the issue is not caused by current or previous Windows monthly updates. The issue has been observed on Samsung Galaxy Book 4 and Samsung Desktop models running Windows 11, versions 24H2 and 25H2, including NP750XGJ, NP750XGL, NP754XGJ, NP754XFG, NP754XGK, DM500SGA, DM500TDA, DM500TGA, and DM501SGA.

Mitigation: 

The affected Samsung Galaxy Connect application was temporarily removed from the Microsoft Store to prevent further installations. Samsung has republished a stable previous version of the application to stop recurrence on additional devices. Recovery options for devices already impacted remain limited, and Samsung continues to evaluate remediation approaches with Microsoft’s support.

Next steps:

Microsoft is collaborating with Samsung’s efforts to develop and validate solutions for devices that have already been affected. We will update this documentation as more information becomes available and Samsung releases further public guidance. For device specific assistance, please contact Samsung’s support channels.

So. We're still waiting for a resolution!

I've tried all of the above alternatives, and it just doesn't work.

Samsung Galaxy Connect or Samsung Continuity Service might cause loss of access to the C: drive

If Samsung Galaxy Connect or Samsung Continuity Service is installed and your Samsung device is experiencing an issue where you lose access to the C: drive and encounter app failures, please follow these steps

Before you start

Plan for 10–15 minutes to complete these steps.

You must sign in to Windows using an Administrator account.

If you are uncomfortable doing this, contact Samsung Support and ask them to perform the “C: drive permissions restore” steps.

Step 1: Start the affected system 

Turn on (start) the affected device.

Sign in to Windows.

Step 2: Remove the Samsung app

Select Start > Settings.

Select Apps > Installed apps.

Find Samsung Galaxy Connect (or Samsung Continuity Service)

Select the app and choose Uninstall.

Restart your device.

Step 3: Temporarily allow Windows to repair drive permissions

1. Open File Explorer.
2. Select This PC.
3. Right-click Local Disk (C:), and then select Properties.
4. Select the Security tab, and then select Advanced.
5. Next to Owner, select Change.
6. Type the following, and then select OK: Everyone​​​​​​​
7. Select Yes if prompted.

   Step 2: Remove the Samsung app

   1. Select Start > Settings.
      1. Select Apps > Installed apps.
         1. Find Samsung Galaxy Connect (or Samsung Continuity Service)
            1. Select the app and choose Uninstall.
               1. Restart your device.

   Step 3: Temporarily allow Windows to repair drive permissions

   1. Open File Explorer.
   2. Select This PC.
   3. Right-click Local Disk (C:), and then select Properties.
   4. Select the Security tab, and then select Advanced.
   5. Next to Owner, select Change.
   6. Type the following, and then select OK:
   Everyone​​​​​​​
   1. Select Yes if prompted.

Step 4: Add a temporary permission

In Properties, select Security > Edit.

Select Add.

Type the following, and then select OK:

Everyone

Select OK, and then Yes if prompted.

If multiple security alerts appear, press Alt + C to continue.

Step 5: Restore Windows default permissions

Create the repair file

1. Open Notepad.
2. Copy and paste the following text: BAT  icacls c:\ /grant BUILTIN\Administrators:(OI)(CI)(F)  icacls c:\ /grant "NT AUTHORITY\SYSTEM:(OI)(CI)(F)"  icacls c:\ /grant BUILTIN\Users:(OI)(CI)(RX)  icacls c:\ /grant "NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(M)"  icacls c:\ /grant "NT AUTHORITY\Authenticated Users:(AD)"  icacls c:\ /setowner "NT Service\TrustedInstaller"  icacls c:\ /remove everyone  pause  Show more lines 
3. Select File > Save as.
4. Set Save as type to All Files.
5. Name the file RestoreAccess.bat.
6. Save it to your Desktop.

   Step 4: Add a temporary permission

   1. In Properties, select Security > Edit.
      1. Select Add.
         1. Type the following, and then select OK:
         Everyone
         1. Select OK, and then Yes if prompted.
            1. If multiple security alerts appear, press Alt + C to continue.

   Step 5: Restore Windows default permissions

   Create the repair file
   1. Open Notepad.
   2. Copy and paste the following text:
   BAT  icacls c:\ /grant BUILTIN\Administrators:(OI)(CI)(F)  icacls c:\ /grant "NT AUTHORITY\SYSTEM:(OI)(CI)(F)"  icacls c:\ /grant BUILTIN\Users:(OI)(CI)(RX)  icacls c:\ /grant "NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(M)"  icacls c:\ /grant "NT AUTHORITY\Authenticated Users:(AD)"  icacls c:\ /setowner "NT Service\TrustedInstaller"  icacls c:\ /remove everyone  pause  Show more lines 
   1. Select File > Save as.
   2. Set Save as type to All Files.
   3. Name the file RestoreAccess.bat.
   4. Save it to your Desktop.

Run the repair

On your Desktop, right-click RestoreAccess.bat.

Select Run as administrator.

Select Yes if prompted.

Wait until the process completes.

Restart your device.

After restarting your device

The following should be true: 

Local Disk (C:) opens normally.

Windows system behavior returns to normal.

Drive ownership is restored to Windows (TrustedInstaller).

This process restores Windows default, secure permissions on the system drive and does not access or modify personal files. 

If you still cannot access the C: drive after completing all steps, contact Samsung Support and reference: “C: drive access issue caused by Galaxy Connect app permissions.”

Possible solution found. Within this site there is another thread under the heading (After KB5079473 update, C: drive missing and system tools inaccessible) they're saying the installing Windows 11 update KB5079473, the C: drive became inaccessible for standard users and several system tools stopped opening correctly. Symptoms pointed to broken NTFS permissions and disabled inheritance on C: rather than a hardware or file‑system failure.

Victor Chiareli has give a step-by-step possible solution. I say possible because Ive not tried it as my laptop is still under guarantee and so is going back to the supplier to be fixed. Fingers crossed! But this might help someone else.

Continuo sem acessar nada.... terrível o que está acontecendo @Samsung

Concordo plenamente. Talvez seja melhor entrar em contato com o suporte da Samsung para obter mais orientações.

Hello,

Search for CMD in the search box, right-click and select Run as administrator, then enter the command:

net user Administrator /active:yes

This will create the Administrator account.

Click the Start menu, click the account avatar, select Sign out, and then log in to the Administrator account.

Once logged into Administrator, press Win+R to open the Run dialog, type netplwiz, and click OK.

Select the account that previously had no administrator privileges → Properties, check Administrator, and finally click OK. Then log back into your original account to see if your permissions have been restored.

Can't access administrator privileges.

I replace utilman with CMD. That way I can use net and activate. Administrator account, but even that way is impossible to delete the update

Uninstalling the problematic update is the most direct way to restore functionality.

1. Open Windows Settings and go to Windows Update.
2. Select Update history.
3. Scroll down and choose Uninstall updates.
4. In the list, locate the entry with the KB number that matches KB5079473.
5. Select it and choose Uninstall.
6. Restart the device when prompted.

If Outlook or other Office apps still crash or do not respond after removing the update, also check for and uninstall any very recent Windows updates that coincide with when the issue started, using the same Update history → Uninstall updates path.

If the update does not appear in the list or cannot be removed, use System Restore (if enabled) to roll the system back to a restore point from before KB5079473 was installed.

After the system is working again, pause Windows Update temporarily to prevent the update from reinstalling until Microsoft provides a fix.

---

References:

• Outlook Freezing and Not Responding and Not saving changes when ending the task - Microsoft Q&A
• Outlook keeps crashing - Microsoft Q&A