Updates for macOS are no longer in the Mac App Store as of macOS Mojave; they’ve moved to System Preferences, in the new Software Update panel.
There’s a ton to love about macOS Mojave, which came out Monday, but there are a few changes that might be confusing at first. There’s a recent programs section on the dock, for example, and updates to macOS itself are no longer found in the Mac App Store.
Instead they’re found in the “Software Update” panel in System Preferences.
This replaces the old “App Store” panel, and will list any updates when they’re available. It’s also where you can configure automatic updates—just click the “Advanced” button at bottom-right.
By default pretty much everything is downloaded and installed automatically, but you can change this by unchecking the options here. This might prove important if you have a limited amount of bandwidth, so keep it in mind.
Honestly, I thought it was weird that system updates were even handled by the App Store in the first place, so it’s good to see them in System Preferences. Updates for the operating system itself should not be in a store that sells applications.