In the process of updating my grandson’s new computer (an Acer Nitro V15 laptop) from Windows 8.1 to Windows 10, I ran into the error C1900101-20017—some error about Windows failing to update.
I tried to update it again, but I ended up with the same result–Windows 10 upgrade failed.
Finally, I realized that there is a UEFI firmware interface option called Secure Boot, an operating system protection mechanism against root kits, which could probably be blocking the update. To get to this, I needed to get to UEFI by pressing F2 (your computer may have a different means to get to this) while the computer is powering up.
Once in UEFI, I disabled the Secure Boot option in the Boot tab, saved the settings, and restarted. I again attempted a Windows 10 upgrade, and this time it worked!
If this worked for you, let me know by commenting below.