Update for Windows 11 10.0.26120.1542 Failing | TiWorker.exe 99% CPU

[mrmkk]

The Cumulative Update for Windows 11 Insider Preview (10.0.26120.1542) (KB5041872) update was failing, and the download was stuck at 8%.

Also, TiWorker.exe was using up all my CPU, pegging it at 99%.

I was having this issue like many in this community are posting about and I have solved it if anyone needs help.

Steps to fix:

      0. If TiWorker is running at 99%, use taskmgr to end it's process.

1. Pause updates by clicking "Pause for 1 week" in Windows Update.
2. Download the latest Insider Preview ISO from Microsoft.
   I used "Windows 11 Insider Preview (DEV Channel) 26100.1150"
   (Windows Insider Preview ISO (microsoft.com)
   
   
3. Use Disk Cleanup to clear any update logs, old Windows versions, anything related to the system.
4. Mount the ISO and install it.
5. Once finished, you will be booted into 26100.1150. TiWorker is finally working normally again.
6. For me at least, in 26100.1150, Windows didn't seem to think I was on the DEV channel and was not offering my any updates, except when I went to Windows Update -> Windows Insider Program it would show a big red X as if a newer build is available in windows update, but it would never show up, so I did the following:
   1. Go into the registry and modify: 

      "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsSelfHost\Applicability"

      Ensure that "IsBuildFlightingEnabled" is set to "1"
      (note: if you don't have anything there, you probably need to re-enroll into insider-preview)
   2. In an admin CMD prompt: 

      bcdedit /set {current} flightsigning yes

   3. Reboot
7. Now Windows Update -> Windows Insider Program showed me that I was on the DEV channel with the option to change to Beta/Release Preview. Going back to Windows Update and clicking "Check for Update" finally showed me 26120.1542. Installed it through Windows Update and let it reboot and finalize.

And that's it. Took two OS installs, but I am finally on a stable 26120.1542. 🙂