I have a similar issue with running Xcode 15 built app on iOS 16.6.1. The app runs fine on iOS 17.0.2, but crashes on launch on older version of iOS - did not have this issue with older versions of Xcode dyld[26192]: Symbol not found: _$sSo24OS_dispatch_queue_serialC8DispatchE5label3qos10attributes20autoreleaseFrequency6targetABSS_AC0E3QoSVAbCE10AttributesVSo0a1_b1_C0CACE011AutoreleaseJ0OANSgtcfC Referenced from: <19E02EF7-C05C-3D62-88DC-AC4178A604FA> /private/var/containers/Bundle/Application/DBC3A9EB-A8F8-4AA4-B72C-C4C59D7C2B4E/Bank Greenwood.app/Bank Greenwood Expected in: <E0BB294E-B630-379B-AAC8-D5C0A83A55E6> /usr/lib/swift/libswiftDispatch.dylib

dyld[26192]: Symbol not found: _$sSo24OS_dispatch_queue_serialC8DispatchE5label3qos10attributes20autoreleaseFrequency6targetABSS_AC0E3QoSVAbCE10AttributesVSo0a1_b1_C0CACE011AutoreleaseJ0OANSgtcfC Referenced from: <19E02EF7-C05C-3D62-88DC-AC4178A604FA> /private/var/containers/Bundle/Application/DBC3A9EB-A8F8-4AA4-B72C-C4C59D7C2B4E/Bank Greenwood.app/Bank Greenwood Expected in: <E0BB294E-B630-379B-AAC8-D5C0A83A55E6> /usr/lib/swift/libswiftDispatch.dylib

TSI Case-ID: 4394375

My issue was resolved after I change private static let queue = DispatchSerialQueue(label: "com.greenwood.imageLoaderURLProtocol") to private static let queue = DispatchQueue(label: "com.greenwood.imageLoaderURLProtocol") I would have expected the compiler to give error regarding DispatchSerialQueue not being available prior to iOS 17.0.... This code was adapted from the Apple sample code, which Xcode helped to update for Xcode 15....