How do I fix a malfunction in the Windows 11 shutdown update feature?

"I ran into this issue once when Windows 11 got stuck on the shutdown update screen. In my case, I restarted the system and then checked for pending updates from Settings > Windows Update. Sometimes corrupted update files cause this, so running the Windows Update troubleshooter or clearing the update cache helps. Also make sure your system has enough storage and no background apps are interfering. After doing this, the shutdown update started working normally again."

Seen this exact thing before, the shutdown button and the update page both rely on the same Windows Update service chain, so when it breaks they usually go together.

First thing I'd try is bypassing the Start Menu entirely. Open PowerShell as admin and just run shutdown /s /t 0  if the button's the issue, that'll get you a clean shutdown without touching anything else.

If that works but the update problem's still there, the most likely culprit is a partially-applied update that got interrupted and left things in a weird state. To clear it out, paste this into admin PowerShell:

net stop wuauserv & net stop bits & net stop cryptSvc

ren C:\Windows\SoftwareDistribution SoftwareDistribution.old 

net start wuauserv & net start bits & net start cryptSvc

That wipes the update cache and forces Windows to rebuild it fresh. Then run DISM /Online /Cleanup-Image /RestoreHealth followed by sfc /scannow, do them in that order, DISM first.

What happens if you go into a DOS box as admin and type "shutdown /f /t 0"?

It sounds like a system issue rather than just a UI glitch. Try running the Windows Update Troubleshooter from Settings then open Command Prompt as administrator and run sfc /scannow and DISM /Online /Cleanup-Image /RestoreHealth. After that restart Windows Update services like wuauserv and bits and check if updates are stuck in the SoftwareDistribution folder. If the problem still continues, doing a repair install using the Windows 11 ISO can fix it without data loss.