Windows 11 Insider Preview Feature Update (26220.8754) Install error - 0xc1900101

I was getting the same error, for multiple attempts, but I was able to resolve it, and I suspect at least some of you may have the same culprit.

Not too long ago there was an article about applying a set of registry tweaks to use the "faster" "server" grade NVME Driver instead of the standard one.  Well, with this enabled you get this 0xc1900101, and it's not super obvious.

After the setuperr.log and setupact.log did not contain any useful driver failure messages, CoPilot helped determine the failure was happening pretty early on in the boot process which triggered the rollback.

Removing the registry tweaks posted here: https://www.ghacks.net/2025/12/26/this-registry-hack-unlocks-a-faster-nvme-driver-in-windows-11/

Then restart  and apply the update for 26220.8754.  For me it worked.