After building our app with Xcode 27.0 (27A266a), we observed that it crashes immediately at launch on devices running iOS versions below 17. Devices running iOS 17 or later appear unaffected by this issue. The previous release, built with Xcode 26, worked on older iOS devices. Deleting and reinstalling the affected app does not resolve the crash. Build settings: Minimum deployment target: iOS 15.0 Swift language mode: Swift 5 Configuration: Release Two crash reports from iOS 16.3.1, covering separate app builds produced with Xcode 27, show the same error: Exception Type: EXC_CRASH (SIGABRT) Termination Reason: Namespace DYLD, Code 4, Symbol missing Symbol not found: _$ss12_ArrayBufferV19_getElementSlowPathyyXlSiFyXl_Ts5 Referenced from: Topi.app/Topi Expected in: /usr/lib/swift/libswiftCore.dylib (terminated at launch; ignore backtrace) The symbol demangles to: generic pre-specialization <Swift.AnyObject> of Swift._ArrayBuffer._getElementSlowPath(Swift.Int) -> Swift.AnyObject The system launch screen appears, then dyld terminates the process before application startup code executes. We have not yet isolated whether the reference comes from compiler-generated application code or a linked dependency, nor completed a same-source comparison between Xcode 26 and 27. Is this a known Swift runtime compatibility issue with Xcode 27 when targeting iOS below 17? Is there a supported fix or workaround that preserves iOS 15 and 16 support?

When I build the app with xcode 13.4.1 it doesn't crash