Windows 11 KB5077181 leaves some Samsung PCs unable to access C: drive, Microsoft confirms

Microsoft has confirmed a Windows 11 known issue affecting some Samsung PCs after the February 2026 security update KB5077181 and later updates. According to the company’s Windows release health page, affected devices can lose access to the C: drive and show the error “C:\ is not accessible – Access denied,” which can block files and prevent some applications from launching.

Microsoft says the issue affects some Samsung models on Windows 11 24H2 and 25H2

On its official Windows 11, version 25H2 known issues page, Microsoft says the problem has been observed on some Samsung Galaxy Book 4 and Samsung Desktop models running Windows 11 24H2 and 25H2. The company lists affected hardware including NP750XGJ, NP750XGL, NP754XGJ, NP754XFG, NP754XGK, DM500SGA, DM500TDA, DM500TGA, and DM501SGA.

Microsoft says users on affected systems can run into the issue during ordinary tasks such as opening files, launching applications, or performing administrative actions. In some cases, users may also be unable to elevate privileges, uninstall updates, or collect logs because of permission failures.

Microsoft and Samsung blame the Galaxy Connect app, not Windows updates themselves

The most notable part of Microsoft’s disclosure is that the company says the issue is not actually caused by current or previous Windows monthly updates, even though reports surfaced around recent Patch Tuesday timing. According to Microsoft, its joint investigation with Samsung found that the symptoms were caused by an issue in the Samsung Galaxy Connect app.

That distinction matters because the problem is tied to systems that installed KB5077181, the February 10, 2026, cumulative update for Windows 11 24H2 and 25H2, and later updates, but Microsoft is framing the root cause as Samsung software rather than the Windows update package itself.

Microsoft says mitigation is already in place

Microsoft currently lists the issue as Mitigated. As part of that mitigation, the company says the affected Samsung Galaxy Connect app was temporarily removed from the Microsoft Store to stop additional installations. Microsoft also says Samsung has republished a stable previous version of the app to prevent the issue from recurring on more devices.

Recovery options for PCs that have already been hit remain limited, however. Microsoft says Samsung is still evaluating remediation approaches with Microsoft’s support and advises affected users to contact Samsung support channels for device-specific help.

The issue was opened on March 13 and last updated on March 14

Microsoft’s release health page says the issue was opened on March 13, 2026, at 12:13 PT and last updated on March 14, 2026, at 16:59 PT. For now, further updates can be found here.