So, I updated Ableton 10 to Ableton 11 and decided I could safely uninstall Ableton 10 lite. Unfortunately, I soon discovered that this removed my "default factory packs" folder and certain packs vanished or needed an upgrade. I was getting an error message "cannot install pack since the default factory pack folder is not available".
So, after searching for similar forum posts - I couldn't find anything that matched my particular dilemma. But - I took a guess and created an Ableton folder where I remembered it should be on my F:/ drive and inside that I created a folder called "packs" ... that, so far, seems to have solved the problem. xx fingers crossed - they are upgrading successfully.
I did have to uninstall those packs that needed an upgrade before - reinstalling them.