Apparent software signing issue breaks updates for some Studio Displays
Enlarge / Apple’s Studio Display.
One thing that makes Apple’s Studio Display monitor unique—aside from the native 5K display resolution—is that there’s basically an iPad inside of it. The monitor includes an Apple A13 chip and 64GB of storage to power some of its smart features, and like any of Apple’s other iDevices, it can receive iOS-based firmware updates to add new features and fix bugs.
But also like Apple’s other iDevices, this means that you’ll sometimes run into problems installing the latest updates for your Studio Display. That was the case over the weekend for some users of the new Studio Displays from Apple who found that they couldn’t update the factory firmware (version 15.3) to the latest version (15.4).
The reason the update stopped working is likely related to how Apple handles iOS software updates. Apple verifies an iOS update file’s digital signature before allowing installation to prevent the installation of updates that contain malware or other modifications. And to prevent downgrading to older iOS versions, Apple will typically only allow installation of the one or two most recent iOS updates at any given time. When a new iOS version is released, as iOS 15.4.1 was on March 31, Apple will stop signing the previous version (in this case, iOS 15.4) shortly after.
The problem for the Studio Display was that it didn’t get a 15.4.1 firmware update along with other iDevices. In and of itself, this isn’t a problem, since the Studio Display doesn’t connect directly to the Internet and isn’t subject to the same security vulnerabilities that a typical iPhone or iPad is. But it was a problem for people receiving new Studio Displays that shipped from the factory with firmware version 15.3 installed. Connected Macs could see that the displays weren’t running the latest firmware version, but Apple was no longer signing iOS 15.4, so the displays couldn’t actually install the update once it was downloaded.
As of April 10, Apple appears to be signing the 15.4 update for the Studio Display again, allowing firmware updates to install normally. These updates are signed on a per-device basis so that older iPhones and iPads can continue to install the latest software version that they support, which means that Apple will normally be able to release new iOS updates without needing to update the Studio Display and vice -versa. In the case of the 15.4 update, as Macworld suggests, it’s possible that Apple simply forgot that it needed to keep signing the update for the Studio Display.
Firmware 15.4 was the version that our review unit was running when we tested it, so it doesn’t include promised fixes to the Studio Display’s mediocre webcam picture quality. According to Apple’s release notes, version 15.4’s main feature (aside from “minor stability improvements”) is support for Boot Camp on Intel Macs.