Search code examples
iosobjective-ccore-datacrashfault

"Core Data could not fulfill a fault" for objects that were not deleted

For a recent update to an app, I am seeing many crash logs with the error that core data could not fulfill a fault. But nowhere in the app (startup, or elsewhere) did I delete the objects whose faults cannot be fulfilled, nor would they have been cascade deleted. How else can this error be happening? And is there a way to catch it and fix it within the live app?

Could it also be if you added but did not properly save the object yet?

Solution

  • It is possible that an object that was not "properly" saved to cause this behaviour.

    One way to do that is:

    • Insert an object in a child context
    • obtain a permanent ID for that object
    • save to the parent context
    • obtain the object in the parent context
    • refresh the object in the parent context
    • access the object in the parent context (fulfil a fault for that object)

    Edit:

    Another way to reach this state in a single context architecture is:

    • Insert an object
    • obtain a permanent id for the object
    • refresh the object
    • try and access the object (trigger a fault on the object)

    the refresh might be a result of a fetched results controller paging through the data and not necessarily something "visible" in your application.

    In addition, there is a CoreData "bug" that not always allows you to catch this exception in a parent-child context architecture, but you can try ...

    However, if this is the scenario you encounter, this is not a desired behaviour for your application. you are loosing the new data added to the store.