Apple has now resolved the firmware problem, and it looks as though the reason it happened is a rather embarrassing one for the company.
Apple hasn’t confirmed what caused the problem, but Macworld believes Apple’s iOS team forgot the Studio Display runs iOS and therefore requires access to the latest updates. On Friday, Apple stopped signing iOS 15.4 because 15.4.1 was the latest version all devices should be downloading. Therefore 15.4 was no longer available to download. The problem seems to be the Studio Display not being granted access to 15.4.1 and the 15.4 update no longer being available, which triggered the error message when an update was attempted.
The fix comes in the form of Apple making iOS 15.4 available for the Studio Display again, so anyone attempting an update now shouldn’t see the error message anymore.
