Troubleshooting Windows 8

0xc000021a PC Ran into problem and needs to restart

0xc000021a PC Ran into problem and needs to restart

This error is commonly known to appear after Windows fails to install a new Windows Update, in most cases the update will keep failing and you will be stuck in a endless loop of restarting. This post can possibly help you overcome this problem.

Troubleshooting the Problem

Boot into Safe Mode

You’ll first need to boot into Safe Mode, you can read how to do that in this post: Boot into Windows Safe Mode in Windows 8

Then open an Elevated Command Prompt:

  1. Open Start
  2. Type CMD
  3. Right-click on Commandprompt and choose Run as Administrator

or Boot into Windows Recovery Environment

Or if you can’t reach Safe Mode then start Windows Recovery Environment, you can read how to do that here: Boot into Windows RE

You’ ll then need to start an Elevated Command Prompt:

  1. Click on Troubleshoot
  2. Click on Advanced Options
  3. Click on Command Prompt
  4. Choose your operating system
  5. Choose your account

Entering the command prompt commands

We have now reached Command Prompt, in this Windows we going to enter three commands that will hopefully solve your problems.

  1. Type: “DISM /image:C\ /cleanup-image /revertpendingactions”
  2. Then type: “move C:\Windows\WinSxS\pending.xml C:\Windows\WinSxS\pending.old”

Restart your system and see if it now boots again.

[symple_box color=”red” fade_in=”false” float=”center” text_align=”left” width=””] In some cases the Windows drive will be labelled X. If using C: gives you troubles then try X first.

Hopefully the problem has been solved using these steps.


  • Rob February 10, 2016

    Well I’m a editor and I was recently rendering a completed edit on my old computer. Even if old my acer laptop has lasted me 5 years and I have had worse problems then this (at least it turns on). While rendering I noticed is was oddly slow compared to how it normally runs. So I canceled the render and let my comp sleep for a day. To come back to a BSOD. I have Windows 10, even though mine was originally vista. I have been through this screen trouble shoot options all day, none working. I have tried all the commands in run and coming back to a error2 or a 87. I went threw the boot options and well you can see where I’m going with this. Any suggestions?

  • Zanxnaz January 31, 2016

    I’m on a reboot Windows 8 upgraded to 10 on a brand new computer… Error 0xc00021a.

    There is no way to get it to boot into Safe Mode because it is not recognizing the F8 key command. I tried to reboot from the disc and the USB and it’s not recognizing anything.

    I have removed all external hardware and rebooted the computer and reattached the monitors, keyboard and mouse and nothing works.

    I hate MS and they should be held accountable for this error. It’s definitely a software issue.

    Any other suggestions?

    • Yuri Pustjens February 1, 2016

      Hello Zanxnaz

      Please make sure that you have your boot priority set to boot from removable devices first instead of your primary hard disk. Also, most systems have a button to press that gives them Access to the boot menu. Mine is F12, some have F8, try to see if your computer starts which button it says, if it says it at all.

      Which computer brand and model do you have? Perhaps I can give you some instructions

  • Leo Mendes January 5, 2016

    I can’t reach CMD because I can’t even boot my OS.
    How can I do this without being able to boot my system up?

  • Vivek Pandya December 17, 2015

    Thank you for the solution it helped me a lot once again thank you.

  • DavidClark October 20, 2015

    There should be a backslash after drive and colon. Like “/image:C:\”

  • MrGrieves October 8, 2015

    Hey! First off, THANK YOU!! This page is a life saver for me!

    Secondly, there’s a typo in the DISM command. It should read as “dism /image:c:” not “dism /image:c (that second “:” is super important)

    Thirdly, any chance that you know how to get past this issue? This problem occurs EVERY time I reboot my VM. Your solution helps me get it booted up, but I basically have to do this every day. Is there a way to permanently resolve this issue so that I don’t have to revert my pending actions every time?


  • Michael September 13, 2015

    Hello yuri
    I tried your fix yor this on my window 10 desktop, and after the first command i get “error 2
    Unable to access image
    Make sure that the image path and the windows directory for the image exist and you have read permission on thia folder”
    I am lost at this point. Can you tell me what to do? Thank you in advance
    Michael Marcus

  • Mir September 10, 2015

    THNX!! my laptop with W10 works again

  • Paula Hutchings July 18, 2015

    LIFE SAVER! I have been surfing the web, posting to computer forums and stressing over the continuous BSOD, never ending restart, repair computer loop. Now to get my back up imaging back on track again. I am now going to bookmark this site as it has been the only helpful tool to my problem.

  • Glenn Sneddon July 18, 2015

    Thanks for your great instructions. It solved my problem perfectly after a failed Windows 8,1 update!

  • Ginie de Vries June 30, 2015

    Will alleen my data on the hard disk be safe? Or will I loose everything on it?

    • Yuri Pustjens June 30, 2015

      Hello Ginie, you doing a refresh or reset? With refresh all data should be safe but backups are highly recomnended

    • Yuri Pustjens June 30, 2015

      Hello Ginie, you doing a refresh or reset? With refresh all data should be safe but backups are highly recomnended.

  • Erick D May 1, 2015

    So here is what I get on step #1; Server 2012 R2 VM
    the cleanup-image option is unknown.

    Has ANYONE managed to resolve this?

    • MAX May 6, 2015

      yeah I have. i posted what i did on another page asking about this problem but it sounded confusing last time i read it. a lot of ppl are having different degrees of what works. some are basic and just restart, but mine was the worst kind, nothing worked. I found that you basically have to look up windows updates from the cmd prompt and find the update that did it and delete it. i did mine early in 2015 so i chose to delete them all from that year and it worked. google how to locate and delete updates from cmd prompt for whatever system you have and try that.

  • Pablo Mazza March 13, 2015


  • Jack Johannson March 4, 2015

    Mega props on this, worked like a charm, saved me from losing all my
    data. Good job.

  • Ryan Patrick February 23, 2015

    I get error 2 when I follow this step by step. Very frustrating:( any help?

  • LoveAngelG February 16, 2015

    Omg after 4hrs of looking for a solution and attempts. I
    finally found one!
    Thank you soooo much literally saved my life! 🙂

  • Ultihood Ulti February 16, 2015

    I can’t understand a ducking thing

  • Osaid -Y February 13, 2015

    didnt work for me ):

  • Calvin Alfredo February 7, 2015

    Hey can you help me pls when i input the code u typed, it didnt work
    instead it show a message “unable to access the image. make sure the image
    path and the windows directory for the image exist and you have read
    permissions on the folder.”
    help me pls

  • Cláudio Albamonte February 7, 2015

    Thank you very much! It helped me in my japanese notebook! Liked and
    subscribed! 😀

  • oscar j February 5, 2015

    after first command i get error 2, also my command promt has x:\windows\system32>

  • Mike B B January 29, 2015

    your my hero, thanks a lot man.

  • Alex Bryant January 26, 2015

    My server will not connect to the command prompt after clicking on the
    administrator profile and typing in the password. It gets stuck on the
    *checking* symbol and will remain there until I reboot… anybody have

  • Sunil Kumar January 20, 2015

    So, after we do this, we still have updates left to install. And if I
    install them, I run into the same issue again. So, we did not really get
    out of the update loop now did we?

    More fundamental question is: why is Windows update making people’s
    computer unbootable?

  • Max xaM January 17, 2015

    Thank u sooooo much! U are a lifesaver

  • Zerocoolan January 16, 2015

    Works perfectly! Thank you, I have been fighting this error for hours.

  • Bunongboyz January 15, 2015

    Thanks dude. This method was the only one that worked for me. What kind of
    update does this…kinda dumb if u ask me.

  • Melinon January 15, 2015

    Thanks a bunch, this really helped!

  • samson swila January 15, 2015

    Yuri, you are the Best, it worked, I inserted the CD, went to Command
    prompt, did the DISM… command and the computer booted

  • martin tari January 14, 2015

    I love you man!!! It works!!! Thank you very much!!!

  • Helmi January 8, 2015

    Hi, after we type instruction number 2 into to the command prompt and press enter, do we wait for the command prompt to exit itself or we manually exit it?

    • Yuri Pustjens January 8, 2015


      It could take some time but a new line should appear where you can enter text as soon as that appears the command has been executed and you can safely close it.

  • Dowser January 7, 2015

    Well, the console says that cleanup-image option is unknown (error 87).
    Then if i type DISM.exe /image:C:\ /cleanup-images /? it gives me a list of options/arguments, starting with the revertpendingactions command. Weird…

  • Manuel January 6, 2015

    Dude, I did it exactly like you said, but when I rebooted still got the same error. Know what happened?

    • Yuri Pustjens January 6, 2015


      Please use our ask help system to ask questions the comments are only meant for feedback, however, what message do you get, please describe as best and precise as possible

  • Diego Urbina Lebrón October 28, 2014

    +Yuri Pustjens Thank you for this post. Just to let you know that this
    will also work with Windows Server 2012 R2. If you have a Cluster of
    Servers running in Windows 2012 R2 and one of the VM’s also running Server
    2012 R2 are not properly shut down due to power failure or human error, and
    the server was in the middle of an update, this kind of error ( 0x000021a )
    can occur. Follow this same steps and verify the letters of your drives.
    Some times you have to change the C:\ for D:\ . When you submit the first
    command, it will take a while for the process to run. Just wait and leave
    it running until it finishes. Then run the second command and you are set.
    When the server restarts, the screen will be black for a while but let it
    run, it is reverting the changes on the background and depending on the
    amount and impact of the updates, the time will vary. Note: You have to
    boot the server from the CD or Image in Hyper-V so when you get to the
    command prompt, you automatically land on X:\Sources and then run the
    commands. Note: You have to boot the server from the CD or Image in
    Hyper-V so when you get to the command prompt, you automatically land on
    X:\Sources and then run the commands.

  • TT Robinson September 29, 2014

    Leaving the correct spaces is critical. Took me 3 times to get it right. Thankfully it worked, very grateful for the advice.

    • Yuri Pustjens September 29, 2014

      Its indeed very important!

    • Rod November 17, 2014

      Error 2 showing up

  • Yuri Pustjens September 6, 2014
  • congusbongus July 28, 2014

    There should be a colon after the drive letter in the DISM command, as in “DISM /image:C: /cleanup-image /revertpendingactions”. C is the drive where windows is installed.

    • Yuri July 28, 2014

      Hello Congus,

      You are indeed correct. I edited the guide 🙂 Thank you!

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