Cannot install Windows 11 - Error 0xc1900101

I got my system upgraded, it had to do with a bad driver being installed for my realtek 2.5gb family controller. The driver being installed was version 1.0.0.7 and it was failing to upgrade, I was lucky enough that my motherboard also has an Intel NIC so I disabled the realtek in the BIOS and deleted it's driver from device manager and the system upgraded perfectly. Not everyone has two NICs but you may be able to do the same thing if your system has a wifi controller. I will update my feedback post so hopefully they can get this corrected, although it's been an issue for a few months now....

Although that would certainly work, my expectation would be that it work without issue. I am not irritated by the regular prompting to install windows 11, I am irritated by it failing every time.

As I did not get a response from Microsoft on the 0xc900101 error, I gave up after fighting this problem for the better part of two days. I was hoping to do the upgrade to the development version of Win 11 from an existing, working, Win 10 machine with normal applications on it. As that effort failed after many tries and lots of experimentation, I took the advice of another poster to this forum. I wiped the NVMe drive clean (removed all partitions), and did an install with a fresh copy of Win 10 (21H1) on a USB 3.0 flash drive. I then immediately put the OS into the development channel, and installed Win 11 without a problem. Unfortunately, I will have to reload all the applications and configuration that the machine had acquired over the last year, but that was the price of being able to install Win 11 on that particular PC. It does seem to work fine, but I would have like to be able to do a straight upgrade from a working machine, as opposed to having to do a clean OS install, and then do the upgrade. Fortunately, I am well organized when it comes to keeping installation software and the license information, so I am able to restore the PC to normal operating condition. Win 11 seems to work well with bluetooth, various third party applications (browsers, performance test software, adobe acrobat reader, Microsoft remote access, Gdata Internet Security, Malwarebytes, Passmark Diskcheckup, and the latest AMD drivers for their 3200G processor and B450 chipset, Having worked in the IT/computer hardware/network protocol development/test engineer business for 50 years (yes I am really that old), I have gotten quite good at finding bugs.

Interesting theory. Disabling devices/drivers seemed to work for you, but I have disabled all 3rd party applications that start with a boot (doing a clean boot), disabled 3rd party antivirus/security stuff, uninstalled stuff that I could not disable, and loaded the very latest drivers for the AMD chipset and AMD graphics my motherboard is using, but have had no luck. Still waiting for a suggestion from Microsoft or a patched version of the installer to fix this. My install and rollback took less than 1/2 hour, but I am using very fast hardware (NVMe with PCIe ver. 3.0 drive for a boot drive).

Good point: I checked and the update is "ready to download." I thought it had tried at least twice on its own, but maybe I did something to trigger those attempts. I'll leave it like that and hopefully won't have to deal with long reboots/re-attempts. Maybe if they push a new release it will install correctly. This does give me a chance to decide if I want to install this preview build, knowing that at the end of the preview I'll have to do a clean re-install of Windows 10.