Windows 10 issue.
Windows 10 issue.
Ensure you remove the old folder after upgrading since it consumes around 20GB of space
Just putting on my tech support hat here for a second... Even though it's not designed to delete data doesn't mean it can't in exceptional circumstances. If you have data you cannot live without back it up before proceeding. Errors happen... I've updated 5 machines without a single issue myself but you never know.
Sure, here are some additional details. (Make sure to keep this in mind)