How to fix
KB5021234 fails to install
on Windows

Hello. I tried to install the new KB5021234 update for Windows 11 but the process fails every time I try. Is there anything I can do?

On December 13, 2022, Microsoft released a new security update for Windows 11 - KB5021234. This update addresses an issue that affects remote networks, specifically an issue that prevents the reconnection to remote networks using DirectAccess. This issue arises when the decryption of a certificate's private key fails, which may be caused by encrypting the DPAPI master key with a wrong value. This failure may also affect VPNs and other 802.1 certificate-based authentications.

However, some people may have issues when trying to install the newest update. There are user reports that KB5021234 fails to install. It is unknown why exactly this may be happening. However, most of the time, Windows updates fail to install because of corrupted files, third-party antivirus interference, or malfunctioning Windows services.

In this guide, you will find 6 steps that should help you fix KB5021234 fails to install in Windows 11. If you want to avoid a lengthy manual troubleshooting process, you can use a maintenance tool like [d1]. It can automatically fix most system errors, BSODs,[ref en-1] corrupted files, registry[ref en-2] issues, or clear cookies and cache.[ref en-3] Otherwise, follow the step-by-step instructions below.

Method 1. Fix Corrupted System Files

Use Command Prompt commands to repair system file corruption:

• Open Command Prompt as administrator
• Use the following command and press Enter:
  sfc /scannow

• Reboot your system
• If SFC returned an error, then use the following command lines, pressing Enter after each:
  DISM /Online /Cleanup-Image /CheckHealth
  DISM /Online /Cleanup-Image /ScanHealth
  DISM /Online /Cleanup-Image /RestoreHealth

Method 2. Disable Third-Party Security Software

Sometimes antivirus software can block legitimate processes mistakenly. You should try disabling your antivirus and trying to run the update again.

Method 3. Run the Update Troubleshooter

• Click the Windows button and select Settings
• Select System from the left pane, then scroll down on the right pane, and click on Troubleshoot
• Click on Other troubleshooters

• Locate the Windows Update troubleshooter and hit the Run button

Method 4. Restart Windows Services

• Type services in the search bar and launch the Services utility
• Find Windows Update in the list
• Double-click on it, set the Startup type to Automatic, and click Apply
• Now click on Restart the Service

• Do the same with Background Intelligent Transfer Service

Method 5. Reset Windows Update Components

• Open the Command Prompt as an Administrator
• Type the following commands one by one and press Enter after each:

• net stop bits

  net stop wuauserv

  net stop cryptsvc

  Del “%ALLUSERSPROFILE%\Application Data\Microsoft\Network\Downloader\qmgr*.dat”

  Ren %Systemroot%\SoftwareDistribution\DataStore DataStore.bak

  Ren %Systemroot%\SoftwareDistribution\Download Download.bak

  Ren %Systemroot%\System32\catroot2 catroot2.bak

  sc.exe sdset bits D:(A;;CCLCSWRPWPDTLOCRRC;;;SY)(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;BA)(A;;CCLCSWLOCRRC;;;AU)(A;;CCLCSWRPWPDTLOCRRC;;;PU)

  sc.exe sdset wuauserv D:(A;;CCLCSWRPWPDTLOCRRC;;;SY)(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;BA)(A;;CCLCSWLOCRRC;;;AU)(A;;CCLCSWRPWPDTLOCRRC;;;PU)

  cd /d %windir%\system32

  regsvr32.exe atl.dll

  regsvr32.exe urlmon.dll

  regsvr32.exe mshtml.dll

  regsvr32.exe shdocvw.dll

  regsvr32.exe browseui.dll

  regsvr32.exe jscript.dll

  regsvr32.exe vbscript.dll

  regsvr32.exe scrrun.dll

  regsvr32.exe msxml.dll

  regsvr32.exe msxml3.dll

  regsvr32.exe msxml6.dll

  regsvr32.exe actxprxy.dll

  regsvr32.exe softpub.dll

  regsvr32.exe wintrust.dll

  regsvr32.exe dssenh.dll

  regsvr32.exe rsaenh.dll

  regsvr32.exe gpkcsp.dll

  regsvr32.exe sccbase.dll

  regsvr32.exe slbcsp.dll

  regsvr32.exe cryptdlg.dll

  regsvr32.exe oleaut32.dll

  regsvr32.exe ole32.dll

  regsvr32.exe shell32.dll

  regsvr32.exe initpki.dll

  regsvr32.exe wuapi.dll

  regsvr32.exe wuaueng.dll

  regsvr32.exe wuaueng1.dll

  regsvr32.exe wucltui.dll

  regsvr32.exe wups.dll

  regsvr32.exe wups2.dll

  regsvr32.exe wuweb.dll

  regsvr32.exe qmgr.dll

  regsvr32.exe qmgrprxy.dll

  regsvr32.exe wucltux.dll

  regsvr32.exe muweb.dll

  regsvr32.exe wuwebv.dll

  netsh winsock reset

  net start bits

  net start wuauserv

  net start cryptsvc

• Wait for the process to finish and restart your PC

Method 6. Repair Install Windows

• Visit the official Microsoft website to download Windows 11 Installation Media
• Run the Media Creation Tool and select Create Installation Media for another PC
• Select your USB drive
• Let the Process complete of writing the Installation files to the USB drive
• Click Finish
• On the PC you wish to upgrade, Press Windows + E to open the File Explorer
• Open the Removable drive and click Setup.exe

• Accept the license terms on the next screen
• Confirm the Upgrade options – Files, apps and Settings are kept
• Click Install, and the upgrade should start