Windows 10 Pro update fails

Question

I'm unable to update my personal Windows 10 and have ran out of ideas to fix it. My current Windows configuration:

• Edition: Windows 10 Pro
• Version: 21H1
• Installed on: ‎11.‎10.‎2020
• OS build: 19043.1202
• Experience: Windows Feature Experience Pack 120.2212.3530.0

Problem occurred approximately a month ago after I had an issue when booting Windows. Windows failed to boot, so I tried various native Windows recovery options. One being deleting the most recent Windows update/patch. Unfortunately none of the Windows recovery options worked and I was left with only with an option to restore my previously done full image backup with Acronis True Image. After restoring Acronis image I was able to boot to Windows normally and everything seemed to work fine — until I tried updating my Windows.

When trying to update, I am offered the cumulative update no. KB5006670. Also waiting in the line is optional update no. KB5006738. The KB5006670 update installation progresses until 20% and then interrupts with the following error message:

There were some problems installing updates, but we'll try again later.
If you keep seeing this and want to search the web or contact support for information, this may help: (0x800f0831)

Retries don't work, so I tried to find a solution by Googling the error code 0x800f0831. It lead me to Microsoft web page https://docs.microsoft.com/en-us/troubleshoot/mem/configmgr/error-0x800f0831-installing-update. I followed the instructions and tried to manually download and install the update no. KB5006670 (and also no. KB5006738) from Microsoft Update Catalog https://www.catalog.update.microsoft.com/Home.aspx. Both manual update installations fail with a following message:

Some updates were not installed. The following update was not installed: 
Security Update for Windows (KB5006670)

Retries don't work. I also tried to run the sfc scannow and DISM and here are the results:

C:\WINDOWS\system32>DISM.exe /Online /Cleanup-image /Restorehealth

Deployment Image Servicing and Management tool
Version: 10.0.19041.844

Image Version: 10.0.19043.1202

[==========================100.0%==========================]
Error: 0x800f081f

The source files could not be found.
Use the "Source" option to specify the location of the files that are required to restore the feature. For more information on specifying a source location, see https://go.microsoft.com/fwlink/?LinkId=243077.

The DISM log file can be found at C:\WINDOWS\Logs\DISM\dism.log

C:\WINDOWS\system32>sfc /scannow

Beginning system scan.  This process will take some time.

Beginning verification phase of system scan.
Verification 100% complete.

Windows Resource Protection did not find any integrity violations.

Currently I'm left on a situation where I'm unable patch my Windows at all. Any ideas what to try next? I'd rather not restore my Windows to "factory settings". Any help would be greatly appreciated, thank you very much.

EDIT 20.11.2021:

@Ramhound. Please find below Windows update logs from path %systemroot%\Logs\CBS. I am not a Windows logs expert, what should I be looking for? Should I also export the .etl files? (I did check them and they seem to contain huge amount of rows, even from only straight after boot).

2021-11-20 14:07:35, Info                  CBS    TI: --- Initializing Trusted Installer ---
2021-11-20 14:07:35, Info                  CBS    TI: Last boot time: 2021-11-20 13:07:19.229
2021-11-20 14:07:35, Info                  CBS    Starting TrustedInstaller initialization.
2021-11-20 14:07:35, Info                  CBS    Lock: New lock added: CCbsPublicSessionClassFactory, level: 30, total lock:4
2021-11-20 14:07:35, Info                  CBS    Lock: New lock added: CCbsPublicSessionClassFactory, level: 30, total lock:5
2021-11-20 14:07:35, Info                  CBS    Lock: New lock added: WinlogonNotifyLock, level: 8, total lock:6
2021-11-20 14:07:35, Info                  CBS    Ending TrustedInstaller initialization.
2021-11-20 14:07:35, Info                  CBS    Starting the TrustedInstaller main loop.
2021-11-20 14:07:35, Info                  CBS    TrustedInstaller service starts successfully.
2021-11-20 14:07:35, Info                  CBS    No startup processing required, TrustedInstaller service was not set as autostart
2021-11-20 14:07:35, Info                  CBS    Startup processing thread terminated normally
2021-11-20 14:07:35, Info                  CBS    TI: Startup Processing completes, release startup processing lock.
2021-11-20 14:07:35, Info                  CBS    Starting TiWorker initialization.
2021-11-20 14:07:35, Info                  CBS    Lock: New lock added: TiWorkerClassFactory, level: 30, total lock:2
2021-11-20 14:07:35, Info                  CBS    Ending TiWorker initialization.
2021-11-20 14:07:35, Info                  CBS    Starting the TiWorker main loop.
 2021-11-20 14:07:35, Info                  CBS    TiWorker starts successfully.
 2021-11-20 14:07:35, Info                  CBS    Lock: New lock added: CCbsWorker, level: 5, total lock:3
 2021-11-20 14:07:35, Info                  CBS    Universal Time is:     2021-11-20 12:07:35.928
2021-11-20 14:07:35, Info                  CBS    Loaded Servicing Stack v10.0.19041.1310 with Core: C:\WINDOWS\winsxs\amd64_microsoft-windows-servicingstack_31bf3856ad364e35_10.0.19041.1310_none_7e15ec207c87d405\cbscore.dll
2021-11-20 14:07:35, Info                  CBS    Build: 19041.1.amd64fre.vb_release.191206-1406
2021-11-20 14:07:35, Info                  CSI    00000001@2021/11/20:12:07:35.934 WcpInitialize: wcp.dll version 10.0.19041.1310 (WinBuild.160101.0800)
 2021-11-20 14:07:35, Info                  CBS    Lock: New lock added: CCbsSessionManager, level: 11, total lock:9
2021-11-20 14:07:35, Info                  CBS    Lock: New lock added: CSIInventoryCriticalSection, level: 64, total lock:10
2021-11-20 14:07:35, Info                  CBS    NonStart: Set pending store consistency check.
2021-11-20 14:07:35, Info                  CBS    Session: 30924295_882671711 initialized by client WinMgmt, external staging directory: (null), external registry directory: (null)
2021-11-20 14:07:36, Info                  CBS    Appl:Feature On Demand package without explicit comparator, using GE on build version
2021-11-20 14:07:36, Info                  CBS    Appl:Feature On Demand package without explicit comparator, using GE on build version
2021-11-20 14:07:36, Info                  CBS    Package Format: PSFX
2021-11-20 14:07:36, Info                  CBS    Package Format: PSFX
2021-11-20 14:07:36, Info                  CBS    Package Format: PSFX
2021-11-20 14:07:36, Info                  CBS    Appl:LCU package and revision compare set to explicit
2021-11-20 14:07:36, Info                  CBS    Package Format: PSFX
2021-11-20 14:07:36, Info                  CBS    Session: 30924295_882671711 finalized. Reboot required: no [HRESULT = 0x00000000 - S_OK]
2021-11-20 14:09:37, Info                  CBS    Trusted Installer is shutting down because: SHUTDOWN_REASON_AUTOSTOP
2021-11-20 14:09:37, Info                  CBS    TiWorker signaled for shutdown, going to exit.
2021-11-20 14:09:37, Info                  CBS    Deleting the contents of directory: \\?\C:\WINDOWS\CbsTemp
2021-11-20 14:09:37, Info                  CBS    Deletion of: \\?\C:\WINDOWS\CbsTemp successful
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: ExecutionEngineFinalize
2021-11-20 14:09:37, Info                  CBS    Execution Engine Finalize
2021-11-20 14:09:37, Info                  CBS    Execution Engine Finalize
2021-11-20 14:09:37, Info                  CBS    Lock: Lock removed: TiWorkerClassFactory, level: 30, total lock:3
2021-11-20 14:09:37, Info                  CBS    Lock: Lock removed: CCbsWorker, level: 5, total lock:2
2021-11-20 14:09:37, Info                  CBS    Ending the TiWorker main loop.
2021-11-20 14:09:37, Info                  CBS    Starting TiWorker finalization.
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: ExecutionEngineFinalize
2021-11-20 14:09:37, Info                  CBS    CBS Engine already deactivated
2021-11-20 14:09:37, Info                  CBS    CBS Engine already deactivated
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: ComponentAnalyzerFinalize
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: PackageTrackerFinalize
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: CoreResourcesUnload
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: SessionManagerFinalize
2021-11-20 14:09:37, Info                  CBS    Lock: Lock removed: CSIInventoryCriticalSection, level: 64, total lock:10
2021-11-20 14:09:37, Info                  CBS    Lock: Lock removed: CCbsSessionManager, level: 11, total lock:9
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: CapabilityManagerFinalize
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: PublicObjectMonitorFinalize
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: Enter vCoreInitializeLock
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: WcpUnload
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: DrupUnload
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: CfgMgr32Unload
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: DpxUnload
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: SrUnload
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: CbsEsdUnload
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: CbsTraceInfoUninitialize
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: CbsEventUnregister
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: AppContainerUnload
2021-11-20 14:09:37, Info                  CBS    CbsCoreFinalize: WdsUnload, logging from cbscore will end.
2021-11-20 14:09:37, Info                  CBS    Ending TiWorker finalization.
2021-11-20 14:09:37, Info                  CBS    Ending the TrustedInstaller main loop.
2021-11-20 14:09:37, Info                  CBS    Starting TrustedInstaller finalization.
2021-11-20 14:09:37, Info                  CBS    Lock: Lock removed: WinlogonNotifyLock, level: 8, total lock:6
2021-11-20 14:09:37, Info                  CBS    Ending TrustedInstaller finalization.

EDIT 2: I solved the problem by using "Windows 10 Upgrade tool" found here https://www.microsoft.com/en-us/software-download/windows10ISO which upgraded my Windows to 21H2. I assume this upgrade included all the relevant updates and after that I haven't encountered any update problems.

Answer 1

Try rebooting in safe mode. Some people report that that fixed it.

Another person claimed that an in-place upgrade worked for them (but not for everyone) https://www.reddit.com/r/techsupport/comments/qmka4t/cannot_install_kb5006670_update_see_post_for/hjlqwou/?utm_source=reddit&utm_medium=web2x&context=3

Answer 2

As I mentioned in the original edited question: I have solved the problem by using "Windows 10 Upgrade tool" found here https://www.microsoft.com/en-us/software-download/windows10ISO which upgraded my Windows to 21H2. I assume this upgrade included all the relevant updates and after that I haven't encountered any update problems anymore. This thread can be thus closed.