macOS: Cannot connect to app store 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.
So the culprit was Little Snitch blocking a process called commerce. If you deny access to commerce then the App Store will refuse to load. Allow it to make all well again: