It seems for whatever reason inverse relationship needs to be explicitly defined. Change from this: @Relationship(deleteRule: .cascade) var tasks: [MyTask]? = [] to @Relationship(deleteRule: .cascade, inverse: \MyTask.todo) var tasks: [MyTask]? = [] has solved the crash issue. Works both in iOS 17.3 and 17.4.

I have now identified that this issue is happening due to Relationships in my model. My MyToDo has task defined like this: @Relationship(deleteRule: .cascade) var tasks: [MyTask]? = [] and MyTask has reference back as following: var todo: MyTodo? Both of them are optional as required for CloudKit. This model can be read in iOS 17.3, but in 17.4 beta, it crashes!

Widget can obtain the data without error/crash from modelContainer using this code: guard let modelContainer = try? ModelContainer(for: MyTodo.self) else { return [] }

My model do not have any @Attribute(.unique) All properties have default values Relationships are marked as optional App is using CloudKit for iCloud syncronization A brandnew app with the same model does not have this issue. When I uncheck "CloutKit" in Signing & Capabilities, the app launch normally.

I dont have an answer and don't know how to generate 5.5" screenshots. However, Apple clarified that those are needed :( https://developer.apple.com/forums/thread/719822

Same problem with me as well. Neither alignment, nor .timer works.