This update provides a preview of improvements to the service technology on Windows 11, version 24H2.
How to Get Windows 11 Build 26120.1252 (KB5038603)?
What if Windows 11 Build 26120.1252, KB5038603 Fails to Install?

Go toStart > controls > System > Troubleshoot > Other Troubleshooters.
Click theRunbutton next toWindows Updateon the right panel.
This Windows Update troubleshooter will run and automatically fix the found issues.

Go to Windows Update to check for updates and see if KB5038603 can install successfully.
Way 2.
Delete the Old Windows Update Files
The previous Windows installation files can cause a failed Windows update.
you’re free to refer to this post to do this:How to Delete Windows Update Files?
Way 3: Run CHKDSK
Step 1.
Run Command Prompt as administrator.
Typechkdsk C: /finto Command Prompt and press Enter to run it.
TypeYin the Command Prompt and pressEnter.
Step 4. start your machine, and then CHKDSK will run to find and fix issues.
This tool is thebest free data recovery softwarefor Windows.