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Windows 8.1 - Error 0XC000021A after optional updates


New Member
Hi All..

I was reviewing my windows updates and saw two optional updates that were pending. First one was for MS office and it went through fine. Second one was some update to AMD vision control center. During that update screen flashed couple of times and went for re-start. After that I am unable to get into the system. I tried safe mode/debugging/low resolution mode etc.. But all resulted in the same blue screen with the 0xc000021a error message.

I am able to go only to command prompt. Nothing else (fortunately I am able to backup my photos by connecting external hard drive and using command prompt). I checked the SRT log file but it doesn't say any issue. All passed.

I tried refresh PC but it came back and said "There was a problem refreshing your PC. No changes made".

I tried using win ISO image bootable flash drive. It couldn't get through me in (I just tried with PC repair option when I booted with ISO image).

Is there a way I can get over it without re-installing?

Thanks in advance...

Krishnan V

My Computer

System One

  • OS
    windows 8.1
    Computer type
    System Manufacturer/Model


New Member
Power User
Canon City

STEP 1: Enter cmd
STEP 2: Now in the Command prompt just type System Root\System32\Drwtsn32.exe -I”. This process will register the Dr.Watson as the default system debugger which has to be -> Press Enter.
STEP 3: Again type System Root\System32\Drwtsn32.exe and then in the window choose the option which are Append to existing log file, Create crash dump and Visual Notification.
STEP 4: After setting it up restart the computer by pressing F8 in the startup and select Last known good configuration.
STEP 5: Once it got booted up, again restart the system in the normal and now try to look at your optional updates to make sure not to install whatever may have broken it before.

If this does not work then you may have to reinstall.

My Computer

System One

  • OS
    Windows 8.1 Pro 64 Bit
    Computer type
    System Manufacturer/Model
    Sager NP2740
    Intel Core i7 4702HQ 2.2 GHz
    8 GB 1600 MHz
    Graphics Card(s)
    Intel Iris Pro 5200
    Sound Card
    High Defenition Audio
    Monitor(s) Displays
    IPS Display
    Screen Resolution
    Hard Drives
    Samsung SSD 840 EVO 250 GB mSATA
    Internet Speed
    60 Mbps cable, NETGEAR Night Hawk AC1900
    Firefox 38.0.5
    Windows Defender & Malwarebytes Pro

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