A recent Windows 10 update has introduced a potentially dangerous bug to CHKDSK, an integrated system file checking utility.
While Microsoft is yet to respond to the bug reports, the number of users reporting issues with CHKDSK increases.
Running CHKDSK May Corrupt Your File System
The Windows 10 December 2020 Patch Tuesday update appears to have inadvertently introduced the CHKDSK bug. The issue will affect any Windows 10 machine running the latest version of the operating system, 20H2.
CHKDSK is a Windows system utility. You can run CHKDSK from the Command Prompt to scan your file system for corrupt files and bad data. The utility can fix issues it encounters using a series of parameters, and the tool is handy for fixing a range of issues that can affect Windows 10.
The BornCity blog first reported on the issue.
The blog explains that running CHKDSK with the repair function can cause a bluescreen error. The crash screen carries the stop code NTFS FILE SYSTEM, indicating an error with the file system.
The affected person was able to observe this on seven computers with Windows 10 20H2. When analyzing the affected disks (SSDs) on a working system, it could be determined that the logical Windows drive on the disk was detected only as a RAW partition. The /f option of chkdsk probably destroyed the NTFS file system.
Further analysis of the drives revealed specific errors attributed to a file called "9" plus an error in the Master File Table's BITMAP attribute.
Microsoft is yet to respond to the error reports, which means the current advice regarding the CHKDSK NTFS file system bug is limited.
At the current time and until Microsoft advises otherwise, you should refrain from using CHKDSK. If you must run CHKDSK for any reason, you should strongly consider making a system backup before proceeding.
Windows 10 Update Introduces Bugs
Long-time Windows users won't be surprised about a Windows Update introducing bugs to the operating system. The Windows 10 December 2020 Patch Tuesday is no different.
However, the CHKDSK bug wasn't being reported as a common issue. Rather, post-update issues included CPU spikes when opening and closing programs, application errors when launching programs on AMD hardware, and the usual complaints about blue screen errors.
Another issue relating to the update is affecting VMware Workstation virtual machines. A Reddit post details the issue, explaining that after installing the update, the workstation experienced an "instant BSOD [blue screen of death] with "System_Service_Exception," with repeated crashes.
In the meantime, avoid using CHKDSK and keep your eyes peeled for any Windows 10 fixes.
