Thanks for the quick answers and explanation. In trying to suss this out I had added NSArray.self to the ofClasses: parameter and no joy. var newParts: Parts? newParts = try NSKeyedUnarchiver.unarchivedObject(ofClasses: [Parts.self, NSString.self, NSArray.self], from: newData) as? Parts The Swift Array in question is a member of the class Parts() and were encoded without NSSecureCoding - would that be a factor? (these archives were created from an earlier version of the app that I'm trying to migrate to Apple's deprecation de jour world) var pageUsesClearBackground: Array<Bool> = [true, true, true, true] coder.encode(pageUsesClearBackground, forKey: "CB_KEY") The plot thickens. Further down the line as things are being decoded I'm finding things that were encoded() are not decoding() - they return nil as well. macOS 14.0 is one sharp corner I must say.

This just started happening out of the blue on a M1 Studio Mac with Monterrey 12.6.7 and XCode 14.1. The project is at least 3 years old and this warning has never shown up. One thing that is interesting is I move the project between the Studio Mac and an intel iMac every now and then. While trying to figure out what's gone wrong now - I happened to look up at the menu bar in XCode and it was saying to run the app under Rosetta. Changing that from My Mac (Rosetta) to My Mac solved the problem. No idea how that got changed.

Anyone ever figure this one out?

I'm getting the same error when playing the moveToTrash.aiff sound with AVAudioPlayer(contentsOf: url). It worked before Monterrey. Maybe after Apple gets done with the next round of emojis they could look into this.