[SOLVED] Re: Core Data: attempt to insert nil key exception on save:

FROM : Paul Collins
DATE : Fri Jun 23 19:23:48 2006

Some of the objects in the model did not belong to the named 
Configuration that the persistent store coordinator was set to use. 
The error was triggered by a relationship defined in the model 
between an Entity that had no Configuration and one that did have a 
Configuration.

A more subtle problem occurs without the relationship property. If 
your persistent store coordinator is coded to use a named 
Configuration, and you save objects that have no Configuration in 
their model definition, the saved XML file has empty strings where 
entity and property names should be, such as  <object type="" 
id="z102">. No exception or error is reported on -save. I don't know 
what happens in the other two file formats. (OS X 10.4.6).

--Paul Collins