After an annoying turn of events where my Windows 10 Enterprise USB drive failed, attempts to install Win10 onto a computer failed miserably. I turned to the net and managed to get my hands on Microsoft's Windows 10 Enterprise Evaluation. I have an enterprise key so I thought - cool! Here's the opportunity to get it going and to then upgrade the license later. Full install, patched etc and all is swell. Except when I try to upgrade.
I straight up tried changing the licence key only to get a variety of errors, most of which are pertaining to the activation system being unavailable. The I try this: https://winaero.com/blog/upgrade-windows-10-evaluation-to-full-version-easily/ but it doesn't work either.
Next I'll try this: http://www.edugeek.net/forums/windows-10/174594-upgrading-windows-10-enterprise-90-evaluation-full.html
And if all else fails, in goes the bootable USB I've now created. If only I'd had this in the first instance I would not be writing this note to myself (and to you).
If only I'd found this: https://www.howtogeek.com/250503/how-to-upgrade-to-windows-10-enterprise-without-reinstalling-windows/ first! I might have been able to dodge much of the problem in the initial stages. Learn from my pain :-)