Apple Watch Series 12 and Ultra 4 Owners Report Unexpected Reboots

Owners of the new Apple Watch Series 12 and Ultra 4 are reporting unexpected reboots. Diagnostic logs point to an Apple Neural Engine timeout: it hangs for about two seconds before a firmware watchdog triggers a kernel panic. The issue appears on both watchOS 27.0 and the day-one update, and Apple has not yet acknowledged it.

• About 30 owners reported random reboots in the MacRumors forums thread
• panic-full logs show the same Neural Engine timeout of around two seconds
• Reboots occur while using Siri AI, Maps, the App Store and recording workouts
• Erasing and replacing the watch did not help: one Series 12 unit showed the same panic