A significant bug in Windows 11 has left many users unable to access their main C: drive, prompting an official acknowledgment from Microsoft. The issue appears to stem from the February 2026 security update (KB5077181) and predominantly affects laptops manufactured by Samsung. Users encountering the problem are met with the error message, “C:\ is not accessible – Access denied,” rendering their systems nearly unusable.
Microsoft has stated that it is currently investigating the issue in collaboration with Samsung. According to reports from Neowin and other sources, the bug may be linked to the Samsung Share app, although this connection has not yet been confirmed. The error significantly hampers access to files, application launches, and administrative tasks, impacting a range of programs including Microsoft Office applications and web browsers.
Scope of the Issue
The bug seems to affect only the latest versions of Windows 11, specifically versions 24H2 and 25H2. Microsoft has indicated that multiple regions are experiencing these issues, including Brazil, Portugal, Korea, and India. Users impacted by this bug have reported that even basic tasks can trigger the “access denied” error, which complicates daily operations and productivity.
For those affected, there are a few potential solutions. Microsoft suggests rolling back the February 2026 update, which can be done through the Settings menu under Windows Update. The company has provided full instructions for this process. Users who have not yet installed the update are advised to temporarily pause it until a fix is available.
Community Workarounds and Precautions
Some users on platforms like Reddit have proposed workarounds that involve changing the ownership of the C: drive. While these methods have reportedly worked for a number of individuals, they carry inherent risks and should be approached with caution. Microsoft has emphasized the need to follow official guidelines and updates as they work to resolve the issue.
The company has promised to release further updates when more information is available, as user frustration continues to grow. For now, affected users should stay informed about potential fixes and monitor official channels for updates on this critical bug impacting Windows 11.
