Updated to 1903 but 'user'.000 now created and holds all my user files

I repaired the damage and continued to use the .000 profile. The only other alternative is to revert back to the previous version before it is too late. Remove Zune. Reinstall 1903.

This might not work for everyone, but I had this problem too, and was able to "fix" it.

I saw that the newly created second username folder only had a few files in it, belonging to Zune. Just as an experiment, I did 2 things:

Firstly, I rolled back windows, and then uninstalled Zune, and removed any old Zune file/folder I could get to (a lot of old Zune files are out of reach because Windows won't let you in those folders), and then restarted my computer freshly.

Secondly, I also unplugged my external hard drives, because someone from Windows had this mentioned in a list of actions I could do, and this was a simple thing to try, so that is why I did it.

Then I let Windows download and install the update (which was now called 1909 for some reason, in stead of 1903), and it worked. I had my normal username folder, and no .000 folder.

So I am not sure which was the exact fix. I remember though that it happened before that Windows 10 updates had problems when hard drives were plugged in, so this could very well be the issue again.

I've just noticed 1909 and installed it on my daughter's computer (which did not have 1903, but she didn't have ZUNE either.  I think I installed that on my PC when years ago I had a Windows Phone!) and there were no problem.

I do wonder whether MS have actually sorted the problem out for the 1909 feature upgrade?  If so, well done MS.

Though it could just be that you had done what several, including myself, did, and removed the ZUNE bits and pieces?

My personal view is that the external HD is a red herring, and that it was ZUNE causing the problem for most of us.