Every time I open the App Store on High Sierra it cannot connect. I've checked the DNS settings, old certificates, keychain access; in short I've completed all these steps and still:
Any ideas? It appears not even to try to load, i.e., that page is immediately there and refreshing doesn't attempt to load anything.
Best Answer
So the culprit was Little Snitch blocking a process called
commerce. If you deny access tocommercethen the App Store will refuse to load. Allow it to make all well again: