Apple releases watchOS 27.0.1 to fix Apple Watch Series 12, Ultra 4 bug

Apple rolled out watchOS 27.0.1 to Apple Watch Series 12 and Ultra 4 owners on Tuesday, promising a fix for an unexpected‑restart bug that began surfacing after the launch of watchOS 27 in early September. The update, which is being pushed automatically to compatible devices, targets a software glitch that could cause the watch to power off and reboot without warning, potentially interrupting health tracking, notifications and other core functions. Apple’s support page lists the issue as affecting a small subset of users, but the company urged anyone experiencing random restarts to install the patch immediately.

The problem emerged shortly after Apple introduced watchOS 27, its most feature‑rich operating system to date, adding new health metrics, a redesigned home screen and deeper integration with iPhone 15 models. Early adopters reported that the bug appeared most often after the watch entered low‑power mode or when a third‑party app accessed the sensor hub. Analysts traced the root cause to a timing conflict in the new “Sleep+” framework, which was meant to improve sleep tracking accuracy. Similar bugs have hit Apple products before, such as the iPhone 14 battery‑drain issue that required a swift iOS 18.1 release, prompting the company to act quickly to preserve its reputation for reliability.

Apple confirmed the fix in a brief statement, saying the update “addresses the unexpected restart issue and improves overall stability.” The company also pledged to monitor crash logs and release further refinements if needed. Users who have already installed watchOS 27.0.1 report that the watches now stay on without sudden reboots, and the patch has already been downloaded by an estimated 2 million devices according to analytics firm Sensor Tower. Retailers say the bug has not affected sales of the Series 12 and Ultra 4, but the incident underscores the pressure on Apple to deliver flawless software alongside its hardware launches. The next scheduled watchOS update, version 27.1, is slated for late October and is expected to bring new health features and performance tweaks, with Apple promising additional testing to avoid repeat issues.