"Access denied" errors on accessing C drive with Samsung laptop (Galaxy Book4)

Hi, good day!

You're not alone as several users experiencing the same problem affecting some Samsung laptops. Microsoft is actively reviewing the issue and working with Samsung to determine the root cause. Please try the workaround below until Microsoft releases an official patch fix.

Make sure you sign-in using a Windows account with Administrator privileges

Open File Explorer > Right click on C: drive

Select Properties > Security > Advanced > Change

On the text box, type Everyone

Click Check Names

Tick the option to replace the owner on subcontainers and objects

Click Change and type and select the "Everyone" option again

Click OK and Apply

When prompted for any warning messages, just click Enter to continue with the process until the full scan of your C drive is complete

Once finish, restart your computer

Delete any files from the recycle bin if prompted.

I look forward to receiving your update and I'm willing to collaborate with you till we resolve the issue. Do keep me informed by clicking "Add comment" below.

The symptoms match a known issue affecting some Samsung Galaxy Book 4 and Samsung Desktop models running Windows 11 24H2 or 25H2, where access to the C: drive is lost and most apps (including Office, browsers, system tools like CMD and Services) fail with “Access denied”.

Key points about this issue:

• It occurs after installing the February 2026 security update KB5077181 (OS Build 26100.7840) and later updates on certain Samsung models.
• Error shown is typically: C:\ is not accessible – Access denied.
• It blocks access to files and prevents launching many applications such as Outlook, Office apps, web browsers, system utilities, and Quick Assist.
• In many cases, elevation, uninstalling updates, or collecting logs also fails because of permission problems.
• Microsoft and Samsung have determined the root cause is an issue in the Samsung Galaxy Connect app, not in the Windows updates themselves.

Current mitigation status and options:

• The problematic Samsung Galaxy Connect version has been removed from Microsoft Store, and Samsung has republished a stable previous version to prevent new devices from being affected.
• For devices already impacted, recovery options are currently limited. Samsung is continuing to evaluate remediation approaches with Microsoft’s support.

What this means for the affected laptop:

• Because access to C: and core tools (CMD, Services, installers like .NET, Office) is blocked by permission failures, normal in-place repair steps are often not possible.
• There is no documented, general-purpose self-service fix in the provided information beyond the mitigation already taken (removing the bad app version from the Store and publishing a stable one to prevent new impact).
• For an already-affected Galaxy Book 4 or listed Samsung desktop model, the next step is to work with Samsung support (and, if available, OEM recovery options) while Samsung and Microsoft finalize remediation guidance.

Until Samsung publishes a specific recovery procedure, the realistic options are:

• Use OEM recovery tools (for example, Samsung recovery environment) if they are still accessible, understanding this may involve repair or reset operations.
• Engage Samsung support directly and reference the known issue with Samsung Galaxy Connect causing C: drive access denial on Windows 11 24H2/25H2 after KB5077181.

References:

• Windows 11, version 25H2 known issues and notifications
• Windows 11, version 24H2 known issues and notifications