Update information Edit(Aug.6)
Today, I upgraded my NJ2100 OS from Windows8.1 Pro(x86) to Windows10 Pro(x86).
I used the media creation tool. This time, I selected the option ‘Upgrade this PC now’ and ‘Keep Windows settings, personal files, and apps’. The PC had just 13.2 GB as free spaces on its C drive. But it brought no problems at the upgrade.