Windows 11 KB5077181 Causes C: Drive Access Issues on Samsung PCs

Microsoft has officially acknowledged a significant issue affecting some Samsung PCs following the installation of Windows 11 KB5077181, the February 2026 security update. The problem, which has been documented on Microsoft's Windows release health page, prevents affected devices from accessing their C: drive, displaying the error message "C:\ is not accessible – Access denied." This critical failure blocks file access and prevents numerous applications from launching, potentially disrupting essential workflows for affected users.

According to Microsoft's official Windows 11, version 25H2 known issues page, the problem specifically impacts certain Samsung Galaxy Book 4 and Samsung Desktop models running Windows 11 24H2 and 25H2. The company has identified several affected hardware configurations, including the NP750XGJ, NP750XGL, NP754XGJ, NP754XFG, NP754XGK, DM500SGA, DM500TDA, DM500TGA, and DM501SGA models.

Users on affected systems may encounter this issue during routine operations such as opening files, launching applications, or performing administrative actions. In more severe cases, the permission failures can prevent users from elevating privileges, uninstalling updates, or collecting diagnostic logs—compounding the difficulty of troubleshooting the problem.

Interestingly, Microsoft has clarified that the issue is not directly caused by the Windows update packages themselves, despite reports surfacing around the recent Patch Tuesday timing. Through a joint investigation with Samsung, the companies determined that the symptoms stem from an issue within the Samsung Galaxy Connect app rather than the Windows update mechanism. This distinction is significant as it shifts responsibility from Microsoft's update process to Samsung's software implementation.

Microsoft has already implemented mitigation measures for this issue. The company reports that the affected Samsung Galaxy Connect app has been temporarily removed from the Microsoft Store to prevent additional installations. Samsung has also republished a stable previous version of the application to minimize the potential for further affected devices. However, recovery options for PCs that have already experienced the problem remain limited.

For users whose systems have already been impacted, Microsoft advises contacting Samsung support channels for device-specific assistance. The company notes that Samsung is actively evaluating remediation approaches with Microsoft's support team. This collaborative effort suggests that a more permanent solution may be in development, though no timeline has been specified for its release.

The issue was formally documented on March 13, 2026, at 12:13 PT and received its last update on March 14, 2026, at 16:59 PT. Microsoft has indicated that further updates regarding this matter will be posted on their Windows release health page.

This incident highlights the complex interplay between operating system updates and third-party software, particularly in the increasingly connected ecosystem of modern PCs. For Samsung users running the affected models, the situation underscores the importance of monitoring official support channels and being cautious about installing system updates until a complete resolution is confirmed.