For me, it turned out to be an issue with the xcodeproj file AND settings. I removed the DVTSourceControlAccountDefaultsKey and also recreated my Xcodeproj from scratch. If you are doing a Swift package that does not require an xcodeproj then just delete it. Very annoying problem to deal with.

Can you print a UTF8 representation of the data?

Having same issue here. They work initially and then randomly stop working. This is on Xcode 13.2 RC

I have found this also to work. Although I think SwiftUI needs a much better way of supporting multiple macOS Windows. In your AppStruct, although any persistent struct or class can hold a window. Limitations: No idea how to let the system determine the window position or whether it will autosave window information. struct Radio_2App: App {     let someWindow = NSWindow( contentRect: NSRect(x: 0, y: 0, width: 580, height: 300), styleMask: [.titled, .closable], backing: .buffered, defer: false)     var body: some Scene {         WindowGroup() { SomeContentView()         }     func openWindow() {         someWindow.contentView = NSHostingView(rootView: SomeOtherView())         self.someWindow.makeKeyAndOrderFront(nil)     } }

I disabled FileVault and also revived the T2 firmware (per albertaki). I'm not sure which one or if both helped but the install finally worked.

Having the exact same issue here. Changing all security settings made no difference.