'An NSManagedObject of class 'className' must have a valid NSEntityDescription.' error
The issue was that I did not checked Class Module: current product module for CDWorkout Entity.
In my case the same problem was in @objc modifier in auto-generated header of data-class
@objc(CachedMovie)
public class CachedMovie: NSManagedObject {
I just removed @objc(CachedMovie)
and it began to work
I had a silly minor issue that resulted in the same error. I was initializing NSPersistentContainer with the incorrect name.
It should have the same name as the source file with the extension .xcdatamodeld. e.g. modelFileName.xcdatamodelId
let persistentContainer = NSPersistentContainer(name: "modelFileName")