macOS, like any other operating system, gets periodic updates. Sometimes these updates add new features but they’re mostly either bug or stability fixes, or they’re security patches. Major macOS updates e.g., the Mojave update for users on High Sierra are downloaded from the Mac App store however, the smaller ones are downloaded from the System Preferences app. Here’s how you can check for, download, and install a macOS update.
Install a macOS update
Open the System Preferences app and select Software Update.
The Software Update preference, when clicked, will automatically scan for any available OS updates.
Once it detects an update, it will show you the version number and if you click the More Info option under it, it will give you additional details about the update. The update, at this point, has only been detected. It will not automatically download and install until you click the Update Now button.
An update can be small, or large. There’s no set rule for it though the size isn’t as big a concern as the installation time is. When you choose to install a macOS update, you also give the OS permission to restart in order to install it. This means that once the update has downloaded, your system will restart. This is why you should only do this if you don’t expect to use your Mac for a while. The installation can take thirty minutes, sometimes even more depending on the size of the update.
You cannot use your Mac when it’s updating. The update screen features the Apple logo, and the loading/progress bar accompanied by a time estimate for how long the update will take. Remember that it’s an estimate and the time can increase or decrease as the update installs.
When the update is complete, you will be booted back to your desktop. If you check for a software update again, it will tell you that your system is up to date, and also which version of the OS you’re running.
If you want OS updates to install automatically when they’re available, click the Advanced button on the Software Update preference, and enable the ‘Download new updates when available’ option, and the ‘Install macOS updates’ option. This will automate both downloading and installation. You don’t have to select them both though. You can set macOS to download available updates but not install them until you choose to.
Note: You can also enable/disable auto updates for iOS if you want.
macOS updates are rolled out to all users at the same time. If you know for a fact that a new update is available but it isn’t being detected, restart your Mac and make sure your internet is working properly. Try using a different internet connection. If an update has just been released, wait a few hours so that Apple’s servers are less busy.