I encountered the same situation, and I found the reason. the reason is symbol definition change in libc++.dylib. in iOS 18.4 above, symbols in libc++abi.dylib are defined as indirect in libc++.dylib. so when building apps, these symbols are marked as defined in libc++.dyilb. but in older OSes lower than iOS 18.4, these are marked as undefined in libc++.dylib. so dyld would meet bad situation. the workaround about this is forcing link order, preceding libc++abi.dylib over libc++.dylib. I filed feedback about this, ticket number is FB17734818