Update to 20H2 - The PC cant run Win 10 We couldnt update the system reserved partition .. Another error 0xc1900201

More details ...0xc1900201

He has a GPT Table

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What are these fonts used for I wonder? EFI\Microsoft\Boot\Fonts  

Windows 10 with GPT partition

1. Search for cmd. Press-and-hold or right-click on Command Prompt in the results, and select Run as administrator.
2. At the command prompt, type mountvol y: /s and then hit Enter. This will add the Y: drive letter to access the System Partition.
3. Switch to the Y drive by typing Y:and press Enter. Then, navigate to the Fonts folder by typing cd EFI\Microsoft\Boot\Fonts. Once there, type del *.* to delete font files. The system may ask you if you are sure to continue, press Y and then Enter to continue

Followed the MS guide like so

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and awaiting results of update .... fingers crossed ...

Current Windows version has reached end of service ...  so had to progress this anyway

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Still waiting on results ... 50 % downloaded ...

That's farther than you got before, right? Good luck!

Try downloading 20h2 as a full Windows install.  Use the media creation tool to download and extract Windows 20h2 to install it.  https://www.yourwindowsguide.com/2020/10/feature-update-to-windows-10-version-20h2.html

Remember if your running window 10 - ver 2004
then this new ‘20H2’ enables some previous existing features (disabled) and only takes minutes
but if you are running the older 2019 version - many folks are indicating it takes hours for the upgrade

so the slow arduous download/build/upgrade may be par for the course

what were you running previously?