Microsoft has officially confirmed a serious bug that affects Windows 11 users on some Samsung devices This article explores samsung problem windows. . After installing the February 2026 security update, the system drive (C:) becomes completely inaccessible.
The business is now working with Samsung to look into the problem. After installing the February 2026 Patch Tuesday update (KB5077181, OS Build 26100.7840), Samsung devices that were affected show the error message: "C:\ is not accessible – Access denied." The error keeps users from accessing their own system drive, which stops applications like Microsoft Outlook, Office apps, web browsers, system utilities, and Quick Assist from starting up. No special operation causes the failure.
Opening files, starting programs, or doing other normal administrative tasks are all that is needed to bring up the error.
In very bad cases, users can't even raise their privileges, uninstall updates, or get diagnostic logs because of cascading permission failures. This makes it almost impossible for them to fix the problem on their own without help from outside sources. Microsoft said that the problem mostly happens on Samsung Galaxy Book 4 and other Samsung consumer devices.
Reports have come in from Brazil, Portugal, South Korea, and India, among other places. Windows 11 version 25H2 and Windows 11 version 24H2 are the only ones affected right now. No server platforms are affected. Enterprise admins have also brought the issue up in the r/sysadmin community on Reddit.
They say that Galaxy Book laptops that are part of Active Directory domains can't have their NTFS permissions changed, even with administrator credentials.
Some secondary failures that have been reported in the field are trackpad driver failures and the inability to open PowerShell because its binary is on the C: drive, which is no longer accessible. Microsoft's most recent investigation points to the Samsung Share app as a likely cause, but the exact cause has not yet been confirmed. The company said it is working with Samsung to find out if the problem is with the Windows update itself or with Samsung's software on the devices that are having problems.
It is thought that the problem has to do with Access Control Lists (ACLs) that are either broken or not set up correctly on the root of the system drive. Microsoft has not yet released an official fix or workaround for the problem, which it has labeled "Investigating" as of March 13, 2026.
A Reddit user who said they were a Samsung technician in Brazil posted an unofficial fix that involved giving the "Everyone" group ownership of the C: drive. However, Microsoft security experts strongly advise against this method because it removes Windows' built-in security protections from important system folders. Microsoft has told users who are affected to wait for an official patch and has promised to keep them updated as the investigation goes on.
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