Apple Watch Series 12 and iPhone 18 Pro Reboots: What’s Fixed and What Isn’t

Soon after launch, some owners of the Apple Watch Series 12, Apple Watch Ultra 4, iPhone 18 Pro and iPhone 18 Pro Max reported devices restarting unexpectedly. The two problems have different symptoms—and, as of September 24, 2026, different fix statuses: the Watch update is available, while the iPhone update is still being prepared. 9122434

Apple Watch: sudden restarts, with a fix available

Watch owners have described the Apple logo appearing without warning before the device restarts. Reports include reboots during calls, workouts and everyday interactions, as well as while the Watch was idle. Some shared diagnostic logs reference an Apple Neural Engine timeout, but those logs do not establish whether the underlying fault is in software, firmware or hardware. Apple has not publicly specified a root cause. 95

Apple released watchOS 27.0.1 on September 23 for the Series 12 and Ultra 4. Its release notes say the update fixes an issue that may cause an Apple Watch to restart unexpectedly; they do not explain the technical cause. 122

iPhone: freezes and reboots after some Face ID failures

Some iPhone 18 Pro and Pro Max owners report that their phones freeze or shut down and then restart. Diagnostic entries described in the reports include “panic-full” logs. One more specific pattern involves a failed Face ID attempt when opening a protected app: 9to5Mac reproduced a freeze and reboot on an iPhone 18 Pro while attempting to access the Passwords app. The publication said the issue did not appear to affect everyone. 24223534

A software glitch in iOS 27 has been suggested, but a Face ID trigger or crash log does not prove the cause of every reported restart. Apple told 9to5Mac that a software update addressing the Face ID-related problem was in development and expected early the following week. As of September 24, that fix had not been reported as released, and Apple had not publicly identified a definitive root cause. 3534

How to install watchOS 27.0.1

On a Series 12 or Ultra 4, open Settings → General → Software Update. You can also use the paired iPhone’s Watch app and go to My Watch → General → Software Update. Before installing, put the Watch on its charger and make sure it has at least 50% battery; keep the paired iPhone nearby. 1233

If an iPhone continues to restart, back it up, check for a software update when Apple releases the promised fix, and contact Apple Support for diagnostics if the problem persists. Owners can look for panic-full or ResetCounter entries under Settings → Privacy & Security → Analytics & Improvements → Analytics Data, but a log entry alone is not a diagnosis. 2234