I've just upgraded my Mum's SP3 via windows update, then after confirming that it was activated, did a clean install.
The same problem appears! Sometimes Windows would not be activated. This is so...

Wow, NickyNails, I never expected to find someone with the same problem!

It's ironic.. I did Win 10 installs on a handful of other laptops in my office, even on my 9 year old laptop and they...

My SP3 was originally on Win 8.1.
I used Microsoft's media creation tool to create a USB installer for Win 10, then upgraded to Win 10 from usb. After upgrading, I verified that Win 10 was...