Some **Windows 11 users have recently encountered a serious problem that prevents them from accessing their main C: drive. The issue appears to be caused by a software bug introduced in the February 2026 security update (KB5077181).
According to reports from Neowin, many affected users see the error message:
- “C:\ is not accessible – Access denied.”
This problem seems to primarily affect laptops made by Samsung.
In an official support note, Microsoft said the bug might be linked to the Samsung Share app, although this has not yet been fully confirmed. What is certain is that the issue prevents users from accessing their hard drives properly and disrupts the normal operation of many applications.
Programs such as Microsoft Office apps and web browsers may fail to launch or function correctly. Microsoft has stated that it is currently investigating the issue in collaboration with Samsung and will release updates once more information becomes available.
Reports also suggest that the bug mainly affects Windows 11 versions 24H2 and 25H2. Users in several regions—including Brazil, Portugal, Korea, and India—have already reported experiencing the issue.
For those impacted, the error can appear when opening files, starting applications, or performing administrative tasks, making their systems extremely difficult to use.
One recommended solution is to roll back the update. Users can do this by going to Settings → Windows Update → Update History → Uninstall Updates and removing the February 2026 update.
If you have not yet installed this update, it may be wise to pause Windows updates temporarily until a fix is released.
Some users on Reddit have suggested alternative workarounds, such as changing the ownership permissions of the C: drive. While this method has worked for certain users, it carries potential risks and should be attempted with caution.
