High Sierra upgrade does nothing at all when opened
Depending on when you downloaded the installer precisely, this answer may provide a clearer reason for the issue.


I have noticed that their have been one or two system updates for macOS High Sierra in the past weeks. The fact that you are encountering this issue is most likely due to the fact that your version is older than the currently available and up-to-date one in the Mac App Store today.
Please try downloading the latest version.


Then let me know how you get on with the install. This would be the only logical reason for it not working on a supported / compatible system.