Apple Watch Series 12 and Ultra 4 Owners Report Unexpected Reboots

Some new Apple Watch Ultra 4 and Apple Watch Series 12 owners are reporting their devices rebooting unexpectedly, and diagnostic logs suggest the crashes are related to the Apple Neural Engine.

Reports have been posted in the MacRumors forums since the new models launched on Friday. Users describe their watches suddenly displaying the Apple logo and restarting while they were interacting with the device, doing things like using Siri AI, editing watch faces, opening Maps or the App Store, starting phone calls, and recording workouts. Some reboots have even occurred when the watch was apparently idle.

Notably, at least four owners have shared “panic-full” diagnostic logs showing the same Neural Engine timeout. In each case, the Apple Neural Engine appears to hang for around two seconds before a firmware watchdog triggers a kernel panic and forces the watch to restart.

The problem has been reported on both the original watchOS 27.0 build and the day-one update that devices downloaded during the setup process. Some users have experienced reboots despite erasing their watches and setting them up as new, and one Series 12 owner said a replacement unit also suffered the same Neural Engine panic.

Around 30 owners have reported random reboots in the MacRumors forums thread so far. Users have also taken to Reddit and Apple Community Support to share similar experiences, so it looks like the problem is pretty widespread. Apple has yet to acknowledged the issue. Have you experienced the problem on a new Apple Watch Ultra 4 or Apple Watch Series 12? Let us know in the comments.