stuartjmz:

markl:

stuartjmz:

gzt: Random suggestion try enabling the 'administrator' user and using that for the install.

but also you cannot know the USB is valid until it works on another machine.

I got the USB from a trusted friend who works as a sysadmin for a big company here, and who's used the same stick to update several machines. He's intrigued by its failure, and wants to come have a look. 

I'd point out also that not all USB install sources are created equal - language, "bitness" (32/64bit), and home vs pro are the three variables that you have to supply when building an install ISO using the media creation tool. If the image on the USB was configured to install an EN-NZ, 64 bit, Pro copy of Win 10, then you're not going to be able to use it to upgrade an EN-NZ 32 bit Windows 8 Home machine for example. 

ALL three have to match exactly. 

Having said that however, when I had created a 32 bit install key mistakenly, and tried to upgrade my 64 bit windows 8.1 laptop with it, I got an actual error message, rather than a silent crash...

I'd suggest building your own install usb, after double checking the bitness, the OS type (pro/home) and the system language for the laptop you're trying to upgrade.

Thanks for your detailed response. I am aware of the issues you raise and in the other threads I reference in the initial post made it clear that I have been unable to create my own install media, which is why I have followed the suggestion made by several commenters and borrowed one.