Windows 10 1803 Update Error 0xc1900101

PCR,

Many thanks for your detailed reply. I will reply to your suggestions and then tell you how I intend to proceed after what you have advised. My points below relate, in the main, to what I did yesterday and not necessarily what I have tried over the course of the last 10 days.

Point 1. Agreed.

Point 2. Yes, I used the assistant yesterday, with bizarre results. The bottom line is that it gets to about 75% in stages as normal, and then reverses backwards to about 35% when it falls over with the message to the effect that it is 'Reverting to the previous operating system'.

Point 3. I will need to check whether KB4023814 is still there, but I did uninstall all that was uninstallable, before last trying.

Point 4. I uninstalled whatever I could in relation to major and semi-major updates....

Point 5. Will do, if these circumstances continue (the PC owner is getting restless, and I am ashamed to say that she has just gone out and bought an Apple computer or something, much against my better judgement).... I suspect that the System Image used previously related to 17.09. Hence there could have been conflicts with the later two versions.... But this approach also raises licence and activation issues. In carrying out these 'repairs' and 'reinstallations' I used the original licence key to activate the first attempt at reinstallation, and the activation was successful but it has generated an entirely different but full 25-character licence key. So when prompted for the licence key on reinstalling, which version should I use and will it work? If a new licence key is required, the owner is unlikely to be willing to fork out for what she (probably mistakingly) regards as 'hers', having paid for the computer assembler/vendor for it originally.

Point 6. First point; may well try. Second point, did this, but may try again.

Point 7. They are not there at present, and I have previously removed them on earlier attempts. I understand what they are for, etc.

Point 8. I may well try this as the point of last resort. Again, I understand the technicalities.

If you can see from my responses that I may have missed or omitted something major, please respond accordingly.

Many thanks for your help, and I will check with the owner to see if she wants me to continue, and if she does, I will report back further in due course.

You are welcome. It sounds like you've been on top of it, but upgrades are tough sometimes. My own upgrade 1803 > 1809 went through all the motions - lots happened - up to a request to reboot to complete it. The reboot was too quick for confidence, but I believed it for including an OOBE (out-of-box experience) on some settings. But the computer actually still was entirely 1803, except it had the ~WS folders & a small Windows.old. Anyway... I removed those & did it manually as in my point 8. That worked very well. I hope it will for her.

Because mine is Windows Home & with a digital entitlement linked to a MSFT account, at "START, Settings, Update & Security, Activation"...

I was never asked for a product key. Even when doing a clean install, it wasn't asked. It just asked for my MSFT account & internet router passwords.

https://support.microsoft.com/en-us/help/12440/windows-10-activation

Activation in Windows 10

The answer to your question must be in there somewhere, if her case is different.

PCR,

Many thanks again.

I am going to wait until the owner decides what she wants to do before I spend anymore time on it. If she wants to receive the PC back to use as a spare, I will format and reinstall from scratch, and just see what, if anything, happens, and then cross the activation issue if and when it arises. I have already made her an offer for the spare parts....

Three additional points. I have seen the ~WS folder occasionally when carrying out numerous previous updates on other machines, but not on this one. I tested the RAM using three different third-party programs, and found no problems. One thing that I experienced with these numerous upgrade attempts on this PC, and on this PC only, is that when it attempted to undertake a warm reboot, it invariably failed and I had to repower-up, after which it carried on regardless....

I am now well into the processes of preparing bootable Windows 10 media in as many forms as our illustrious software publishers permit.

I will report further if indeed there is anything further of relevance to report.

V

You are welcome. Right, if the upgrade-install won't work even done manually, then a clean install is the ultimate step. Here is an URL for that...

https://answers.microsoft.com/en-us/windows/forum/windows_10-windows_install/clean-install-windows-10/1c426bdf-79b1-4d42-be93-17378d93e587

Clean Install Windows 10

It took 26 minutes to do my own clean install, & Cortana was speaking after 17 of them. She asked for my MSFT & Wi-Fi passwords only. The Wi-Fi password is written on the router. Afterwards, Windows was activated & my digital license was intact. If you can't do it that way - Greg has a few paragraphs on activation in there, but it still leads to that URL I posted earlier.

Yes, keep us informed. Good luck.