Core Data -existingObjectWithID:error: causes error 133000

Question

My app uses Core Data (with some help of Magical Record) and is rather heavily multithreaded using NSOperation.

Of course I am very careful to only pass aro

Answer 1

The problem is that NSManagedObjectID you pass is temporary. You can check it by calling NSManagedObjectID's isTemporaryID method. From docs:

Returns a Boolean value that indicates whether the receiver is temporary.

Most object IDs return NO. New objects inserted into a managed object context are assigned a temporary ID which is replaced with a permanent one once the object gets saved to a persistent store.

You should first save your changes to persistent store, only then get a permanent ID to pass to other context.