Apple released watchOS 27.0.1 on Wednesday, just over a week after watchOS 27 reached the public. It only goes to the Apple Watch Series 12 and Ultra 4, and according to Apple it fixes an issue where the watch may restart unexpectedly. You can install it from the Settings app on the watch or the Watch app on your iPhone. The watch has to be on its charger with more than 50 percent battery.
Owners on Reddit and other forums had reported the reboots while editing watch faces, making calls, using Siri AI and recording workouts. A few said it happened while the watch sat idle. One Apple forums post traced a crash to a Neural Engine command that waited 2,020 milliseconds against a 2,000-millisecond limit, per AppleInsider. Apple lists no CVE entries for this release, so it doesn't look like a security update.