Users of popular Mac desktop extension app Duet Display are being advised not to update to macOS 10.13.4, due to "critical bugs" that prevent the software from communicating with connected iOS devices used as extra displays.

When installed on a Mac and an iPad (or iPhone) and the two devices are connected using a Lightning cable or 30-pin connector, Duet allows users to extend their macOS desktop space on the Retina display of the iOS device. However, unspecified changes in the latest update to macOS High Sierra, released by Apple yesterday, causes the Duet client app to hang, and users are being advised to hold back from upgrading, at least for now.



Duet's developers are recommending that users contact Apple through the company's online bug reporting form to get the issue prioritized. In the meantime, the developers are "actively looking" into workarounds to reinstate Duet's functionality in macOS 10.13.4.

Duet Display is priced at $19.99 in the App Store, and unlocking the Pro features to turn the iPad Pro into a drawing tablet costs an additional $19.99 per year through an in-app subscription. Duet Display is available from the App Store. [Direct Link]

Update: Users of other desktop extension apps like Air Display and iDisplay are also reporting incompatibility with macOS 10.13.4. DisplayLink-enabled USB graphics devices are also reportedly affected. There's some speculation that Apple's added eGPU support in 10.13.4 is the underlying cause of the issues. We'll keep readers updated if we hear more.