Cannot install Windows 11 - Error 0xc1900101

I had the same issue. It was just about to complete the update, but then it restarted back to Windows 10 with the 0xc1900101 error in Windows Update. Tried a myriad of things. In the end one of 2 things resolved it for me. I say this as I did both at the same time before I tried the update again. PITA but better than wiping and starting over. I disabled bitlocker and cleared the TPM in the BIOS, and disconnected the monitors from the nvidia quadro card and used the onboard intel display. Tried update again. Success. Re-enabled quadro card and reset Windows PIN and turned bitlocker back on.

I fall back to my prior speculations. Microsoft has taken the position that the configurations of power users, is way too much work at this stage. Baby steps, with simple configurations, then more complex, then a little more, then finally to the types of computers actual DEV level Windows Insiders use.

I just tried dot 120 with no luck. Poop. Short for Pre Optimized Operating Platform.

Thanks for the suggestion. It turned out I did NOT have secure boot enabled so I went through the steps of enabling that in my BIOS and then had to jump through a few hoops (disabling Memory Integrity) because my Intel graphics driver wouldn't load (prevent use of multiple monitors). Once I had everything working again, tried installing the upgrade and it still failed with the same error.

Ensure you have secure boot enabled in your bios or it will cause this error.

I very much appreciate your comments. I have an external M3 that I will clone from the internal M3.

The primary obstacle / challenge I'm facing is that there is in excess of 750gb of data and 30+ applications to contend with. No one is a big fan of moving a train load of data and most certainly not reinstalling dozens of applications. MS is a bit grumpy about licenses being 'used' too many times.

I enjoyed the way you smacked MS up side the head. Politically correct or incorrect. I hope I don't hurt their feelings.