Beginning April 2026, watchOS apps uploaded to App Store Connect must also include 64-bit support and be built with the watchOS 26 SDK. To enable 64-bit support in your project, we recommend using the default Xcode build setting of “Standard architectures” to build a single binary with 64-bit code.
You can test ARM64 compatibility for your apps in the Xcode Simulator, and on Apple Watch Series 9 or 10, or Apple Watch Ultra 2 running watchOS 26 beta.