An unusual new bug that prevents Windows 11 users from accessing their main C: drive on Samsung devices has been identified following a recent system update. A preliminary investigation by Microsoft and Samsung has placed the blame on a Samsung-specific app, rather than an issue with the Windows 11 update itself.
The message “C:\ is not accessible – Access denied” became visible when trying to launch apps or access files on affected devices after installing February 2026 security updates (KB5077181) on certain Samsung devices, including some Galaxy Book 4 laptops and Samsung Desktop models, according to Microsoft in a notice posted online.
