Windows 10: Stop code 0xc000021a when installing KB4343909

Hello


I have been finding that my computer encounters a 0xc000021a stop code when trying to install windows update KB4343909. When looking in the system logs I see the below error message:


"Installation Failure: Windows failed to install the following update with error 0x800F0845: 2018-08 Cumulative Update for Windows 10 Version 1803 for x64-based Systems (KB4343909)."


To return windows to a working state I have to revertpendingactions using dism from the command prompt but I cannot find why this update is causing this issue. I have seen the below in the patch notes and wondered if this was a BIOS issue as my manufacturer isn't release a bios/microcode update for my motherboard and cpu.


"Provides protections against a new speculative execution side-channel vulnerability known as L1 Terminal Fault (L1TF) that affects Intel® Core® processors and Intel® Xeon® processors (CVE-2018-3620 and CVE-2018-3646). Make sure previous OS protections against Spectre Variant 2 and Meltdown vulnerabilities are enabled using the registry settings outlined in the Windows Client and Windows Server guidance KB articles. (These registry settings are enabled by default for Windows Client OS editions, but disabled by default for Windows Server OS editions.)"


I have also noticed this event in the system event log but patch KB4100347 never shows as ever having been downloaded for installation.


"Installation Failure: Windows failed to install the following update with error 0x800F0845: 2018-07 Update for Windows 10 Version 1803 for x64-based Systems (KB4100347)."


Any advice you can advise on what is causing this or what I can do to troubleshoot would be appreciated.

:)

 

Stop code 0xc000021a BSOD

Hi,

The blue screen with the stop code 0xc000021a error that you've encountered can be triggered due to corrupted or missing registry files. To effectively assist you with your concern, we suggest that you boot your device in Safe Mode trough the Windows Recovery
Environment. Here are the steps on how to trigger Safe Mode:

• Turn on your computer.
• When the Windows logo appear, unplug the power source of your computer.
• Perform this step three times. On the fourth time, wait for the Windows Recovery Environment (WinRE) to appear.
• On the Choose an option screen, select Troubleshoot
  > Advanced options > Startup Settings and click
  Restart.
• Once your computer restarts, you will see a list of options. Press the
  F4 key to start your computer in Safe Mode.

Once you're done, wait for your device to turn on and check if you encounter the same issue.

Feel free to post back if you encounter any challenges along the process.

 

0xc000021a Stopcode

Hi Stephen,

One of the possible reasons why you’re getting the stop error code 0xc000021a is because of an incompatible hardware that's connected to the computer. To get started with troubleshooting this, you can follow the suggested fixes provided by
MohammandEskandary on this
thread.

In the event that it doesn't work, we suggest that you check this
article for more troubleshooting steps in resolving this stop code error 0xc000021a.

Let us know if the issue has been resolved. Otherwise, we’ll be here if you need further assistance.

 

stop code 0xc000021a

Thank you for the update. It would be very helpful if you can share us an error code after trying to reset the PC. To help you recall the recent changes, the stop code 0xc000021a is commonly caused by a third party application recently installed. The information
was from this article:
Bug Check 0xC000021A. If you found the same stop code, then
SFC /scannow will be useful.

If we're correct, the stop-code should come up with an entirely blue screen, and it should be stated that an automatic restart will happen after automatically collecting some error information.

Regards.