Windows 11 Update Failed, then Windows Update failed

[RonLyster]

I was just offered the opportunity to upgrade to Windows 11 in the Release Preview Channel. I gladly accepted the offer. The upgrade downloaded, then installed (seemingly 100%), and then rebooted. Windows came back up and it looked exactly the same as before. I checked Windows Update and I was again offered the opportunity to upgrade to Windows 11. I again accepted the offer, the upgrade downloaded, and the machine rebooted. When it came back up I wasn't surprised - the machine was still a Windows 10 Pro version 21H1 (OS Build 19043.1263) machine.
I then tried a simple Windows Update, and rather than finding any updates Windows Update encountered an error. I retried finding updates many times, but I continued to get the error (0xc1900101). The option to upgrade to Windows 11 has disappeared.
I read that it might help to unplug attached devices. I did that for all but my mouse and keyboard and rebooted. Tried doing Windows Update again and got the same error (0xc1900101).
I went to the Insider Program, clicked on "Get Help," opened a chat, and then was directed to post here. Hope someone can help.
My machine is an Intel NUC with Core i7-10710 processor and 64 GB of RAM. It has Windows Feature Experience Pack 120.2212.3920.0.

[#2]

@RonLyster  (probably a bit late, but) The standard fix for this type of windows update error, is to stop the windows update service, then go to C:\Windows\SoftwareDistribution and delete everything. The start the windows update service and look for updates again. Has worked more than 40 times for me on various machines.

[#3]

@EvilJesternz Not too late at all.  I'm giving it a try right now.  Hope it works!

UPDATE:  Unfortunately, it didn't work.  After doing what you suggested I repeatedly get this:  "There were some problems installing updates, but we'll try again later. If you keep seeing this and want to search the web or contact support for information, this may help: (0xc1900101)."  Darn!

Looks like I'll be with Windows 10 for awhile.

[#4 · Accepted solution]

@RonLyster 

It seems that on many computers there is this problem!

Cannot install Windows 11 - Error 0xc1900101 - Microsoft Community