Stop Code 0xc000021a Windows 10 BSOD How I Fixed it and What Caused it

Last month, I faced a blue screen of death (BSOD) when I turned on my laptop with Windows 10 installed. The stop code was 0xc000021a. The automatic startup repair that automatically runs on reboot wasn’t successful. I eventually traced the problem to bad sectors in the hard drive. The computer couldn’t read the data in bad sectors and this resulted in Windows failing to load.

Strictly speaking, I wasn’t able to fix this. You can’t fix the bad sectors’ problem. If your hard drive develops bad sectors, you are left with no choice but to replace the hard drive. That is what I did. I replaced the hard drive.

First, let’s see how I reached the conclusion that this problem was due to bad sectors. I downloaded the Windows 10 ISO file and burned it to a USB drive.

I set the computer to boot from the USB drive. When this screen (see figure 1) showed up, I pressed Shift+F10 to launch the command prompt.

The command prompt showed currently selected partition as X:\

I needed to find the drive letter of the partition where Windows 10 was installed. I ran the following commands one after another (see figure 2).

diskpart
list disk
select disk 0
list volume

In figure 3, you see that Volume 0 is DVD-ROM and Windows 10 setup has assigned it to drive letter J.

Volume 1 is a partition on the hard drive and has drive letter C. This partition has an NTFS file system. This could be the partition where Windows 10 is installed.

I ran the command dir c: to check the contents of this partition. As seen in figure 4, this indeed is the partition where Windows 10 is installed.

To check this partition for bad sectors, I ran the CHKDSK utility program with this command chkdsk c: \r. The \r option tries to locate and recover the readable data from bad sectors. This checking process took around 45 minutes. You can see the results in figure 5.

File record segment 58322 is unreadable.
File record segment 58323 is unreadable.

CHKDSK is scanning unindexed files for reconnect to their original directory.
 3 unindexed files scanned.
 3 unindexed files recovered to original directory.

Windows replaced bad clusters in file 1BE61 of
name \System Volume Information\klmeta.dat.

An unspecified error occurred (6e74667363686b2e b67).
Failed to transfer logged messages to the
event log with status 6.

CHKDSK utility program couldn’t fix the file system of this partition.

Did I lose my data?

No. I didn’t lose any data. I had Ubuntu installed too in another partition of the same hard drive. Ubuntu booted up properly. From there I was able to transfer my data to another hard drive.

I used the Ubuntu Disks utility program to check the health of the hard drive. It showed 8 bad sectors. The hard drive also failed the short test.

Summary

Windows 10 stop code 0xc000021a was caused by a failing hard disk drive. The drive had bad sectors. The data in these bad sectors were unreadable and non-recoverable and thus Windows 10 failed to start up properly.

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