Installation Issues

I am trying to install Cubase 12 on my PC, updated today from Cubase 8 Pro. I deleted all files to do with Cubase 8 from my system for a fresh install. Re-installed Library manager, download assistant etc, and went to download the new software. However when I click to download Cubase to my system it comes up with an error

Error in Method)

Cannot run program “cmd” (in directory “C:\Program Files\Steinberh\Install Assistant”): CreateProcess error =267, The directory name is invalid

I have restarted my PC several Times, re-installed everything, started in safe mode, everything I can think of to fix this issue. Has anyone else had this problem or has Technology finally risen up against me?
Any help greatly appreciated!

What version of Windows? Did you check against the system requirements?

I am having the exact same issue with windows 11 home.

I am having the same problem Nuendo 12 windows 10 I have created new folders and now I dont have the correct permissions, come on Steinberg where is your help that I contacted 3 hours ago?