Ziqiao, thank you so much for this! I can confirm that removing the migrations makes it work. It seems I don't even need to create 2 containers, just by removing the migrationPlan: parameter SwiftData is able to migrate the app model in production to the CloudKit compatible one. I will try to reproduce on the new betas later today. Thanks again and happy wwdc24! Best, Matteo

Thank you for the suggestion! I tried to take a step back with a brand new container and simply specifying it; this is what I get as an error: Unresolved error loading container Error Domain=NSCocoaErrorDomain Code=134060 "A Core Data error occurred." UserInfo={NSLocalizedFailureReason=Unable to find a configuration named 'default' in the specified managed object model.} This happens when there is no name specified in the ModelConfiguration. The model seems fine in terms of CK limits.

Just for future reference, the minimum supporting AppStorage inside ObservableObjects is iOS 14.5 (https://developer.apple.com/documentation/ios-ipados-release-notes/ios-ipados-14_5-release-notes)