Hello,
I'm a bit short on my SSD (9.5 Gb free, on an old 40Gb SSD).
First, I run the assistant: you need at least 8 Gb: OK, I did some cleaning.
Second try: OK, it's downloading... Comodo in safe mode, 360TS ON: after downloading, update fail, you may disable your antivirus and retry...

(no alert on my logs)
Third try: (360 TS OFF, CFW OFF) : you need at least 8 Gb ! The assistant is not cleaning its own directory
Ok, I have removed Windows10upgrade directory... ready to restart the whole process... but...
my friends: how much size your system partition had lost after the upgrade ? I don't want to change my SSD on this old computer...