Windows Update KB5101650 continually failing with 0x800f0920

Question

Windows Update KB5101650 continually failing with 0x800f0920

Bryan King 20

I've been having trouble getting an update to go through for over a month now. I've tried all the basic stuff like resetting Windows Update, including doing the upgrade in place through Windows Update, and then doing it by downloading and installing it via an ISO. When I did the latter without including updates it worked, but then KB5101650 failed again.

It will initially install, but on reset it will get stuck on 97% for an hour or so and then finally fail. The code is always 0x800f0920. Most recently I tried installing the July preview package, which also failed. Today 2026-08 Security Update (KB121003) (26200.9168) and 2026-08 .NET Framework Security Update (KB5120708) failed to install with 0x800f0920.

I have an Intel Core i9-14900KF processor, if that helps. Weirdly, while at 97%, the fans don't blow very hard unless I turn my monitor off. They'll then blow hard like the processor is heavily running.

0 comments

Answer accepted by question author

SD - IA 179K Independent Advisor

I think doing a PC Reset or a Clean install, is the next ideal step I am afraid.

https://pureinfotech.com/clean-install-windows-11/

https://yourwindowsguide.com/2021/09/clean-install-windows-11.html

Standard 3rd party link disclaimer:

There may be links to non-Microsoft websites that provide accurate and safe information. Watch out for ads on websites frequently classified as PUP (Potentially Unwanted Products). There is no need to buy paid products to fix your computers, as they sometimes do more harm than good.

Bryan King 20 Reputation points

2026-08-15T17:40:21.86+00:00

I thought they would eventually be the case. So, I did a clean install, and the latest cumulative update that was getting stuck at 97% was able to be installed. Thanks for all your help.

4 additional answers

Your answer

Bryan King 20 Reputation points

2026-08-15T17:40:21.86+00:00

I thought they would eventually be the case. So, I did a clean install, and the latest cumulative update that was getting stuck at 97% was able to be installed. Thanks for all your help.

Answer 1

SD - IA 179K Independent Advisor

Thank you, this is clear. May I know if a clean boot was tried, as Ramesh suggested?

Bryan King 20 Reputation points

2026-08-13T20:34:05.1133333+00:00

I tried this, stopped all non-MS services and disabled all startup apps, rebooted. It still failed. I first installed 2026-08 Net Framework Security Update (KB5120708) and that worked. Just the 2026-08 Security Update (KB5121003) (26200.9168) failed. These big security updates are the ones that keep failing.

Answer 2

SD - IA 179K Independent Advisor

Hi,
It seems like the registry is corrupt.

000012f9 Warning: HKCU violation: HKCU values are not serviceable, failing key is \REGISTRY\USER\SOFTWARE\Microsoft\Windows\Windows Error

Line 30533: 2026-08-12 08:13:11, Error CBS Startup: A possible hang was detected on the last boot. [HRESULT = 0x800f0920 - CBS_E_HANG_DETECTED]

Did a repair using the ISO completed successfully?

Open Command Prompt as Administrator.
Run:
```
   chkdsk C: /f
```
If C: is in use, Windows will ask to schedule the check for the next restart. Press Y, then restart the PC.

Then,

After the restart, you can retrieve the CHKDSK log from Event Viewer:

Press Win + R, type eventvwr.msc, and press Enter.
Go to Windows Logs → Application.
Select Filter Current Log.
Under Event sources, select Chkdsk and/or Wininit.

Paste the CHKDSK log here.

Bryan King 20 Reputation points

2026-08-12T17:45:47.3633333+00:00
Checking file system on C:

The type of the file system is NTFS.

Volume label is Windows.

A disk check has been scheduled.

Windows will now check the disk.

Stage 1: Examining basic file system structure ...

1415168 file records processed.

File verification completed.

Phase duration (File record verification): 5.98 seconds.

62165 large file records processed.

Phase duration (Orphan file record recovery): 16.68 milliseconds.

0 bad file records processed.

Phase duration (Bad file record checking): 2.11 milliseconds.

Stage 2: Examining file name linkage ...

753 reparse records processed.

1759050 index entries processed.

Index verification completed.

Phase duration (Index verification): 22.58 seconds.

0 unindexed files scanned.

Phase duration (Orphan reconnection): 3.33 seconds.

0 unindexed files recovered to lost and found.

Phase duration (Orphan recovery to lost and found): 5.20 seconds.

753 reparse records processed.

Phase duration (Reparse point and Object ID verification): 9.42 milliseconds.

Stage 3: Examining security descriptors ...

Cleaning up 2715 unused index entries from index $SII of file 0x9.

Cleaning up 2715 unused index entries from index $SDH of file 0x9.

Cleaning up 2715 unused security descriptors.

Security descriptor verification completed.

Phase duration (Security descriptor verification): 35.90 milliseconds.

171942 data files processed.

Phase duration (Data attribute verification): 2.36 milliseconds.

CHKDSK is verifying Usn Journal...

36767624 USN bytes processed.

Usn Journal verification completed.

Phase duration (USN journal verification): 84.89 milliseconds.

Windows has scanned the file system and found no problems.

No further action is required.

1951626239 KB total disk space.

422002664 KB in 543369 files.

461664 KB in 171943 indexes. 0 KB in bad sectors.

1601147 KB in use by the system.

65536 KB occupied by the log file.

1527560764 KB available on disk.

4096 bytes in each allocation unit.

487906559 total allocation units on disk.

381890191 allocation units available on disk.

Total duration: 37.35 seconds (37355 ms).

Internal Info:

00 98 15 00 24 ea 0a 00 90 31 15 00 00 00 00 00 ....$....1......

0b 01 00 00 e6 01 00 00 00 00 00 00 00 00 00 00 ................
Bryan King 20 Reputation points

2026-08-12T17:49:49.11+00:00

Oh, and, yeah, when I did the upgrade in place using the downloaded ISO and did not include updates, that finished successfully. Later, when trying to do an update, the update got stuck at 97% again though.

Answer 3

Ramesh 181.2K Volunteer Moderator

A servicing operation is taking a long time to finish. The servicing stack watchdog timer expires and assumes that the system stopped responding. Extending the timeout value mitigates the issue. Increase the resources on the device. If it's a virtual machine, increase virtual CPU and memory to speed up operations.

Common Windows Update errors - Windows Client | Microsoft Learn

Please clean boot Windows to free up system resources.

A clean boot is the process of starting Windows without loading any third-party applications or services.

Launch msconfig.exe and select the Services tab.
Enable the Hide all Microsoft services checkbox. This is an important step. (Now, the list will contain only 3rd party services.)
Click Disable all.
Click OK. -Open Task Manager (Ctrl + Shift + Esc) and click on the Startup tab. Disable all startup apps.
Restart Windows.

For more information, please refer to the Microsoft article.

How to perform a clean boot in Windows

(Step 3 in the above link is crucial. You need to first enable "Hide all Microsoft Services" before clicking "Disable all".)

Bryan King 20 Reputation points

2026-08-13T20:33:15.3533333+00:00

I tried this, stopped all non-MS services and disabled all startup apps, rebooted. It still failed. I first installed 2026-08 Net Framework Security Update (KB5120708) and that worked. Just the 2026-08 Security Update (KB5121003) (26200.9168) failed. These big security updates are the ones that keep failing.
Ramesh 181.2K Reputation points Volunteer Moderator

2026-08-14T03:00:51.4966667+00:00

Please try this → https://support.microsoft.com/en-us/windows/deployment/install-upgrade/fix-issues-by-reinstalling-the-current-version-of-windows
Bryan King 20 Reputation points

2026-08-14T09:29:41.06+00:00

I already tried that. I also did an upgrade in place by downloading an ISO. Both methods successfully completed, but the update still got stuck at 97%.
Ramesh 181.2K Reputation points Volunteer Moderator

2026-08-14T10:04:31.7766667+00:00

Maybe you can download the latest (26200.9168) ISO from Uupdump.net and run the in-place upgrade again.

https://uupdump.net/selectlang.php?id=6a8c4c24-0dd2-46b9-9d8f-bd7a84ec5ad4

Select the OS language, and click Next.

Select the editions you need, and click Next.

Select "Download and convert to ISO".

Select "Include updates (Windows converter only)"

Click the "Create download package" button.

It downloads a .zip file. Extract the contents of the zip file to a folder.

Run the file "uup_download_windows.cmd" to launch the ISO download.

(The setup image will be downloaded from Microsoft's servers.)

Mount the ISO and run setup.exe to start the repair installation.

Answer 4

SD - IA 179K Independent Advisor

Hi,

An Inplace upgrade should have worked.

To simplify things, please download and let the update fail once. It will leave a trace for the failure.

Then, do the following:

Open your File Explorer and go to your system drive, which is commonly C drive.

Navigate to Windows>Logs>CBS folder.

You may need to check the Hidden items option under the View tab in tool bar to show the Logs folder.

Right-click on the CBS.log file and select Copy.

Paste it to your desktop.

Go to your OneDrive account and upload CBS.log from the Desktop.

Share the link of the CBS log and post it in the next reply.

I look forward to hearing from you to get the results of the troubleshooting.

Bryan King 20 Reputation points

2026-08-12T12:20:37.0033333+00:00

Here's the link: https://1drv.ms/u/c/e3f86e97b737b437/IQA9kMs740KwQKOz6X8LrOaqAZnFiC6h4-IlLlRca9qD81E?e=yewTL4