Slimline Desktop PC Model 270-a0xx won't update past Win 10 1909, Also, DVD stopped working.

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I have a HP Slimline Desktop PC Model 270-a0xx with board HP 82FF 00. Windows 10 update refused to go past version 1909 (to Windows 21H1).
Trying to force an upgrade using Window10 installation media produced this error: Windows 10 Upgrade Error 0XC1900101 – 0x20017. Installation Failed in the SAFE_OS phase during BOOT operation.

I tried numerous suggestions available online but none of these worked. Finally, I manually updated the UEFI (BIOS) firmware — even though HP Support Assistant software told me there were no HP updates available for my computer! I went to https://support.hp.com/us-en/drivers , entered my computer's serial number, and I followed the recommended updating instructions.

I also found numerous other drivers needed to be updated. Most significantly, the DVD drive had stopped working and it was damaging my blank DVDs by writing nonsense. To get the DVD drive to work, I not only had to install the new "Optical Drive" firmware (driver), but I first had to delete the original DVD driver from Windows Device Manager, or else the new driver was installed but nothing changed. After the DVD device was deleted from Device Manager, installing the DVD "optical" update made the DVD player/recorder work perfectly again.

Hope the above helps somebody. In my search, I found several old threads with the same update problem to get past Windows 10 1909. So the key seems to be drivers, starting with the BIOS, regardless of what HO Support Assistant might tell you after scanning your system. The UEFI/BIOS appeared to be the critical issue, but if you are like me there will probably be many other driver updates that need to be done.