Mac apps stuck

Since upgrading to High Sierra, I can’t download or update apps from the Mac App Store, and I don’t receive any system updates either. How can I get these to work again?

[ DENNIS OATES ]

Howard Oakley replies: Check in System Preferences’ iCloud and App Store panes that you’re signed in using your correct Apple ID. Also confirm in the latter that your Mac is at least set to automatically check for updates. If those are correct but the Store still isn’t working, try signing out of it and iCloud and signing in again. The underlying cause is most likely that your upgrade to High Sierra didn’t work correctly and needs to be repeated. Before doing so, ensure you have a good recent backup of the internal drive, in case you need to restore files from there.

If you kept a copy of the ‘Install macOS High Sierra’ app, open it to install High Sierra again over the top of itself. There’s no need to erase the disk, and your current data will be retained. The installer will fix problems with system files that may be your trouble’s cause.

If you no longer have the installer, because the only way to obtain it is from the Mac App Store, your current installation can’t download a fresh copy while the problem persists. In this case, hold ‘Command-R’ at startup to enter Recovery, then choose the ‘Reinstall macOS’ option.

If that doesn’t fix the problem, you can hold ‘Command-Option-R’ at startup; the option to install macOS then installs the latest version, even if it’s newer than what you’re using.