I downloaded the High Sierra upgrade a few weeks ago and have tried to launch it now and then since, but it does nothing. Not even report an error.
It does seem to start. I'm pretty sure I can see it when I run
top in a terminal.
My machine is officially compatible. It's a mid-2013 11" MacBook Air.
It doesn't have an SSD, just a USB 3 external hard drive. But this didn't stop the last few OS upgrades from working.
I can't seem to find this specific problem mentioned anywhere on the net when I Google for it.
Is this actually a known problem with a solution?
I thought I should try to run it from the terminal and see if it outputs an error there. But it is not a regular executable file. It is some kind of magical directory in fact that is associated with the App Store. So I don't know of a way to launch it from the terminal. Doubleclicking on it does something in the background using the App Store, since the App Store does not open or tell me anything.