Windows 10 Update 1903 renames User fiolder

I can confirm that I did the Rollback successfully (before I messed around with any Zune files) and it did seem to put EVERYTHING back to what it was before, with a fully working system.  It did restore the genuine old C:\Users\User folder.

I then paused for a couple of days, decided to try removing Zune files etc., and re-performed the upgrade, successfully the second time.

P.S. Is ANYONE from Microsoft watching this thread.  It would be nice to know what they think about this 'team of amateurs' trying to sort out their mess, and whether they are trying to do anything about it!!

Yes, the rollback to 1809 will restore everything as it was before the upgrade, including all the user profiles. You have 10 days to do this after the 1903 upgrade. After that Windows thinks the upgrade is OK and deletes the old files to save on disk space. After the rollback do what I previously posted, which is:

1. Search on your user profile for Zune files. If you find any, that's probably the problem.
2. If you have them create a local user account with administrator privileges (admin rights).
3. Restart your computer and sign with the new local account.
4. Search in your original profile for the word Zune.
5. Delete all the results. You'll probably have multiple entries in your search results. Just hit retry until all the files are gone. I think it was only one file that caused the problem buts it's easier just to delete all of them since they're not needed.
6. Perform the upgrade. It should work. You can also delete the local account you created above.

I'm giving your suggestion to rollback the upgrade a serious thought because right now the registry has a lot of entries that point to C:\Users\Users.000 folder and surprisingly a large number of entries that point to C:\Users\User as well and I really don't want to mess with the registry if I can avoid it.

One thing I'm not sure about is whether the rollback to 1809 will restore my original C:\Users\User profile or not because it's stuck in the User.000 state right now.  Sounds like in your case it did?

Can you "go back to the previous version of Windows 10" in the "Update and Security" "Recovery" options under "PC Settings"? If it's been more than 10 days since the update this option will be grayed out. Also, if you have Backup turned on you should be able to restore your computer to a time before the upgrade. If you can do either of these, do so and then delete the files and run the upgrade again. When I did the upgrade I had a bunch of files in my original profile that were not in the .000 profile. I reset my system to a pre-upgrade state and looked at these files and I found a Zune file was the only one I couldn't delete. From that profile login I had to "jump through hoops" to delete the file. From another login, with admin rights, I had no problem, since the Zune service never started. You might have to show hidden files in the folder options. I not sure about this last bit since the first thing I do after an installation or upgrade is to show hidden files and not hide file extensions for known file types.

   I highly recommend having Backup turned on and saving to a separate drive on your system, if possible. I also have a USB HDD that I use for running Backup on all my computers about once a month, or before a major update like the 1903 build. The USB HDD also protects against ransomware. Ransomware infects every drive connected to your system. Since the USB HDD isn't connected, there's no way for it to become infected, unless I hook it up to an infected system. These backups do take time but if I ever do get ransomware all I have to do is boot from a recovery drive, nuke the computer's drives, and then restore the system. By nuke I mean deleting every partition on every drive and then creating and formatting new partitions to give me a 'virgin' system. I had an SSD fail about a year ago that was nothing more than a minor inconvenience.

    I do know there are tools like Transwiz that copy profiles but I've never had to use them. You might be able to, from another login with admin rights, copy the .000 profile to a profile with your original name and then rename the .000 profile to something else. This should give you the correct paths when you login.

    I haven't really looked too much into it but it seems the 1903 build moves your profile into a .000 file while checking and removing invalid entries, deletes the folder with the original user name, and then removes the .000. If it finds a file it can't move, like the Zune file, it just stops and leaves you with the two profiles, original and .000, without giving an error. It looks like somebody at MS forgot to account for this.

Similar problem as the original poster about Windows 10 1903 creating a User.000 folder.  My Win10 system was upgraded from Win 7 so there were older applications which may have contributed to the issue. In particular the files that were leftover in the original profile directory were from: Zune, Windows Ink (InputPersonalization), and Plex.  To resolve that I uninstalled Zune, renamed C:\Program Files\Common Files\microsoft shared\Ink folder to "Ink-bak", and stopped Plex from starting on boot.  After deleting C:\Users and rebooting, there were no new files created in that folder.

At this point there are two options:

1. Leave everything as-is, and applications that store the original path C:\Users\User won't know about the changed path, so fix each one individually as discovered, e.g. Outlook, OneDrive, Google Drive, ...
2. Rename the Users.000 folder to Users, then the applications will be OK, but there will be lots of broken shortcuts and other references since Windows has stored them in the registry (as @RobK3 pointed out)

Rebooting the machine several times hasn't coaxed Windows into resuming the process of moving User.000 to User and fixing all the registry entries. I'm planning on doing step 2 but one more step is needs i.e. write a script to find and replace registry entries from Users.000 to Users so that everything is buttoned up nicely...anyone have a script for that?