Apple expands watchOS 27.0.1 to all eligible Apple Watch models

Apple released watchOS 27.0.1 to all eligible Apple Watch models on 28 September 2026, following an initial release last week that covered only the Apple Watch Series 12 and Apple Watch Ultra 4. The update addresses a bug that could cause some devices to restart unexpectedly, and it carries build number 24R365 across all supported models.9to5mac.com+1

The expansion matters because the restart bug previously affected only the newest watches for a week, leaving older but still-supported models running the prior watchOS 27 build. Apple now says every watchOS 27-compatible Apple Watch can install the fix. The company's release notes for watchOS 27.0.1 are unchanged from last week's release, so the stated scope of the update has not widened even as its reach has.9to5mac.com

What the update fixes

Apple's release notes for watchOS 27.0.1 read: "This update provides bug fixes for your Apple Watch including fixing an issue where Apple Watch may restart unexpectedly." The same wording applied to last week's release for the Series 12 and Ultra 4. Apple lists no security fixes in the notes, so the specific nature of any other fixes addressed by the update remains unspecified.

The build number shipped on 28 September 2026 is 24R365, identical to the build Apple released last week for the Series 12 and Ultra 4. A shared build number means all supported watches are running the same compiled software, so the difference between this week's rollout and last week's is which devices can download it, not what the software contains.

The models that gained watchOS 27.0.1 on 28 September 2026 are the Apple Watch SE 3, Apple Watch Series 9, Apple Watch Series 10, Apple Watch Series 11, Apple Watch Ultra 2 and Apple Watch Ultra 3. Together with the Series 12 and Ultra 4 from last week, these cover every Apple Watch model compatible with watchOS 27.

Which models gained the update

Apple's release notes for watchOS 27.0.1 list only "bug fixes for your Apple Watch" and do not name any security fixes, so what the update addresses beyond the restart issue is unclear. The restart fix itself is confirmed: Apple's own notes describe it directly, and both the initial and expanded releases carry the same build number 24R365.

Apple on 28 September 2026 also released iOS 27.0.1, iPadOS 27.0.1, visionOS 27.0.1, iOS 26.7.1, macOS 27.0.1 Golden Gate, macOS Tahoe 26.7.1 and macOS Sequoia 15.8.1. iOS 27.0.1 fixed an issue that could cause some iPhone 18 Pro models to restart when using Face ID; the other updates include additional bug fixes and security improvements.

What remains unlisted

The watchOS 27.0.1 rollout sits alongside Apple's broader 2026 software cycle, in which Siri AI arrived with iOS 27 and its companion updates. Siri AI runs on Apple Watch Series 9 and later, Apple Watch Ultra 2 and later, and Apple Watch SE 3, when paired with an AI-supported iPhone. That hardware list overlaps with the watches that gained watchOS 27.0.1 on 28 September 2026.

Apple has not changed the watchOS 27.0.1 release notes since last week, and the company does not list security fixes for this update. Users installing the update on 28 September 2026 can expect the restart fix and unspecified bug fixes, with no published detail on anything further. No date for a subsequent watchOS 27 update has been announced.