Event Overview
Multiple users of the newly released Apple Watch Ultra 4 and Apple Watch Series 12 report recurrent unexpected reboots. Diagnostic logs confirm the cause: Apple Neural Engine timeouts. This dedicated machine learning processor—responsible for AI tasks like Siri response, image processing, and on-device AI inference—freezes for approximately two seconds; the firmware watchdog then triggers a kernel panic, forcing a reboot and displaying the Apple logo.
| Key Facts | Details |
|---|---|
| Release Date | Last Friday (September 18, 2026) |
| Affected Models | Apple Watch Ultra 4, Apple Watch Series 12 |
| System Versions Affected | watchOS 27.0 out-of-box and first-day update both impacted |
| Crash Log Signature | Identical panic-full logs show Neural Engine timeout |
| Reported Users | ~30 on MacRumors; additional reports on Reddit and Apple Support Communities |
Technical Details and User Reports
Usersdescribe reboots triggered during common activities: invoking Siri AI, editing watch faces, opening Maps or App Store, making calls, or recording workouts. Surprisingly, reboots also occur while the device is idle and unattended, undermining assumptions about usage-pattern dependency.
At least four users uploaded complete panic-full kernel logs, each displaying the identical failure pattern: the Neural Engine stalls for ~2 seconds before the watchdog timer— embedded hardware monitoring that kills unresponsive processes—forces a system reset.
Crucially, the issue persists after factory reset and even after unit replacement. One Series 12 owner reported identical Neural Engine panics on a replacement device, confirming the defect is not attributable to user data corruption or device-specific manufacturing outliers.
Current Status and Scope
Since last Friday’s launch, MacRumors threads have accumulated steadily; Reddit and Apple’s own support forums mirror this surge. The geographic and demographic spread confirms this is a systemic issue, not isolated incidents. As of September 21 (IT之家 reporting date), Apple has issued no public statement or advisory.
This is not a third-party app or jailbreak-related issue: affected devices run clean, unsigned firmware with no root modifications.
Recommendations for Users
- Buy now if: You prioritize rugged durability and extended battery life (Apple’s 72-hour claim for Ultra 4) and can tolerate AI feature instability during early adoption.
- Wait if: Your use case depends on reliable Siri or fitness analytics. Users experiencing frequent crashes should monitor for Apple Watch OS updates; until then, disabling on-device AI acceleration in Settings may reduce reboot frequency.
Final Thoughts
Neural Engine-related instability at launch is不 unprecedented, but simultaneous occurrence across two product lines is unusual. Apple’s aggressive timeline for on-device AI features demands correspondingly rigorous firmware validation—users accept intermittent reboot risk as the trade-off for privacy-preserving, latency-sensitive machine learning on their wrist.