Teknozip – A rather unsettling glitch has surfaced within the Windows 11 ecosystem, leaving some users locked out of their primary C drive. Microsoft has acknowledged the issue, confirming that certain Samsung devices are particularly vulnerable, displaying a chilling "C: is not accessible – Access denied" error following recent Windows 11 updates.
The problem, which appears to have intensified following the installation of the February 2026 security update (KB5077181) and subsequent updates, prevents users from accessing files and launching applications. Affected programs include Outlook, Office apps, web browsers, system utilities, and even Quick Assist.
Microsoft has updated its "Windows 11, version 25H2 known issues and notifications" page to reflect this critical bug. The tech giant is actively investigating the root cause, suspecting a potential conflict with Samsung Share, although definitive answers remain elusive.
Also Read
The issue manifests during routine operations such as accessing files, launching applications, or performing administrative tasks. In some instances, users find themselves unable to elevate privileges, uninstall updates, or collect logs due to permission failures, compounding the frustration.
The problem appears to be widespread, affecting "[the] Samsung Galaxy Book 4 and other Samsung consumer devices."
While Microsoft works on a permanent solution, a temporary workaround has emerged from a Reddit thread dedicated to the issue. Several users have reported success by logging into an administrator account, right-clicking the C: drive, navigating to its properties, selecting the Security tab, and manually granting the user permission to access the drive.
However, it’s crucial to exercise caution when implementing this fix, as it may introduce further instability. Users uncomfortable with this level of intervention may prefer to uninstall the problematic update or patiently await an official patch from Microsoft.