With all the excitement of the iOS 11.3 release, you may not have noticed that Apple also unleashed macOS 10.13.4 on the world. The latest Mac update includes a bunch of smaller fixes, with a focus on "stability, performance, and security", but if you're using Duet Display you should avoid the newest version of macOS at all costs.
Duet Display, a popular app that turns your iPad into a second screen for your Mac, announced this week that a bug in Apple's update blocks the software from working. The company doesn't have a solution at the moment, instead suggesting that you stick with macOS 10.13.3 until a fix is available.
If you've never heard of Duet Display, the app is definitely worth checking out — assuming you have an iPad on hand and you haven't already updated to macOS 10.13.4. All you need is a wired connection and you can turn your tablet into a fully-functional secondary screen running macOS.
The app also adds a MacBook Pro-style Touch Bar to your iPad while it's connected and if your iPad supports the Apple Pencil, it works in Duet Display, too.