I got macOS Mojave (v10.14.3) running on my system.
I am connected through WiFi and I could browse and do other internet-access.
Resolved:
After I connected to my internet (wired), the issue with AppStore, Software Update and google email all got resolved.
Thank you.
Are you using Wifi to connect to your router, if so try an ethernet connection. In Mojave's App Store there is no longer the Featured section, it's been replaced by Discover. Bottom left of the App Store page should indicate whether you are logged in, it should display your avatar and AppleID, if not click Store in the menubar and click Sign In.
If you are trying to update your Mac to 10.14.6 you can download the Combo update here,
https://support.apple.com/kb/DL2010?viewlocale=en_US&locale=en_US
once downloaded double-click to install.
Always make a full back up before installing any new OS updates.
Restart the mac > open Appstore > go to the "Featured page" > login with your Apple ID.
Then go to the Updates page and see what updates there are for you.
A good idea from Eau Rouge Combo Update.
You still have make sure that you know what to do in Appstore; here is a picture of what I said above:
Not resolved:
Opened App Store (still getting the Cannot Connect to App Store message).
Clicked on the App Store icon from the top left corner.
I don't see "Feature page" and don't see any option to login using my Apple Id.
Thank you, but issue is not resolved.
Following are the steps I followed:
Opened App Store (still getting the Cannot Connect to App Store message).
Clicked on the App Store icon from the top left corner.
I don't see "Feature page" and don't see any option to login using my Apple Id.
This is the App Store you now get in Mojave, which the OP is running. No Featured.
Ah, yes, other mbp used. Didn't notice.
Software Update: Unable to check for updates
