watchOS 27.0.1 fixes the Apple Watch restart bug in new devices

Apple’s watchOS 27.0.1 update has arrived with a fix that prevents Apple Watch Ultra 4 and Apple Watch Series 12 models from randomly restarting.

On Wednesday, just over a week after watchOS 27.0 reached the general public, Apple deployed the watchOS 27.0.1 update. The software addresses a bug that caused the Apple Watch Series 12 and Apple Watch Ultra 4 to restart unexpectedly.

Those who encountered the now-resolved issue said their Apple Watch rebooted while editing watch faces, making calls, using Siri AI, opening Apple Maps or the App Store, and recording workouts. Some Apple Watch owners have even said their devices restarted when idle.

As for what caused the reboot bug on watchOS 27.0, an Apple forums post outlined a Neural Engine timeout on an affected Apple Watch model. In short, a Neural Engine command waited 2,020 milliseconds, exceeding a 2,000-millisecond limit, after which the device rebooted.

While the watchOS 27.0.1 update addressed these spontaneous reboots, Apple did not disclose what caused them.

The company’s website says there are no CVE (Common Vulnerabilities and Exposures) entries associated with watchOS 27.0.1. This suggests the software likely doesn’t include major security fixes and that this release did not patch any significant vulnerabilities.

The same page also outlines that watchOS 27.0.1 is available only for Apple Watch Ultra 4 and Apple Watch Series 12. In short, it’s a bug-fix update for the 2026 Apple Watch lineup.

How to update to watchOS 27.0.1

1. Ensure the Apple Watch is charged to at least 50% and connected to Wi-Fi
2. On your Apple Watch, open the Settings app
3. Tap General
4. Tap Software Update
5. Tap Install if a software update is available
6. Follow the on-screen instructions

How to update to watchOS 27.0.1 via iPhone

1. Ensure your watch is charged to 50% and connected to Wi-Fi
2. On your iPhone, open the Apple Watch app
3. Tap General
4. Tap Software Update
5. Download the update if it is available
6. Follow the on-screen instructions