Microsoft has recognized and fixed a bug in Windows 10 that could have caused critical problems on systems running the chkdisk tool. This is a tool that can prove critical in the event of issues on a computer’s storage system: it can be run via command line and allows you to check volumes on a storage device and look for logical or physical errors on file system metadata. By running it on Windows 10 2004 and 20H2, users could have damaged the file system and prevented future access attempts.
The problem, and how to fix it
Microsoft has not yet specified which Windows versions the problems could occur on as a result of running chkdsk, a problem currently reported only on the KB4592438 and KB4586853 update pages released for Windows 10 2004 and 20H2 in December and November, respectively. The bug was reported by Günter Born, after Planet3DNow users had already reported it publicly.
Microsoft explains it this way, “It has been reported that on a small number of devices on which this update has been installed, the file system may become corrupted after running the chkdsk /f command, and the device will no longer boot correctly.” The problem has been fixed according to Microsoft for all unmanaged devices without the need for user intervention, although it may take up to 24 hours for the fix to be rolled out to all systems. To speed up the process, all potentially affected devices can be rebooted after downloading the package reported above.
What to do in case of an already damaged system
For those who have already run chkdsk /f on their system, damaging the file system, you can try to restore the boot by performing some basic steps provided by Microsoft. It is not certain, however, that the steps will lead to a complete restoration of systems functionality:
After a series of unsuccessful boot attempts, the system should be booted into the Recovery Console
From the Recovery Console, select Advanced Options
Select Command Prompt
Type chkdsk /f followed by the Enter key
Wait for the storage drive scan to complete. Once complete type exit followed by the Enter key
The device should boot as expected. If the reboot leads to the Recovery Console select Continue – Exit and continue with Windows 10
Once the steps are complete the system should reboot and scan the primary storage drive once again. Once completed the system operation should return to normal.