Windows won’t let me in-place upgrade to 1903

Hi, I’m hoping that some of you fantastically helpful folks might be able to point me in the right direction.

I’m unable to update to 1903. I’m at work right now so do not have access to the machine, but I get various errors in the Update section of Settings. I went through the trouble of wiping the update history and files, and dowloaded the self-starting Windows Update. This ran (once I had wiped the update history), and got to the point of the install selection, but the first two are greyed out. It will only let me go forward with a clean install. I then tried the ISO by rebooting to a USB drive with a fresh copy of the 1903 update thanks to the media creation tool – but it too will only let me do a fresh install.

I’ve done some searching but things are inconclusive. Many mention language differences, but I’m set to English-US. I have ensured that I have all updates prior to 1903. I have enough room on the drive (which it was complaining about previously).

In order to ensure there was enough room on the drive, I actually moved a good amount of data from c: to d:, thanks to the very helpful folks who answered my questions in this thread. I’ve read at various semi-believable places that perhaps it is this move that is causing the problem. Regardless, I don’t want my drive formatted if I can help it.

Is there anyone that can give me some direction on getting the install to work without forcing it to scrub my drive first? Thank you in advance.

Martin.