managedObjectContext save fails with error being null

Question

What would cause an error to come back null, this is what I have

    + (BOOL)saveContext:(NSManagedObjectContext *)context
    {
      NSError *error = nil;
      if (![context save:&error]) 
      {
        DLog(@"ERROR %@, %@", error, [error userInfo]);
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Sorry"

                                                        message:@"Error Saving the Data" 
                                                       delegate:nil 
                                              cancelButtonTitle:@"OK"
                                              otherButtonTitles:nil];

        [alert show];
        [alert release];

        return NO;
      }
    return YES;
    }

The above method is a class method, I am not sure why the error does not have any information.

This method is called like this

[HSCoreDataUtility saveContext:self.managedObjectContext];

when a modalViewController is closing and returning to the NavigationController, so I need the context to be saved, but it throughs an error, now I think I have an idea as to the cause of it not being saved, but shouldn't the error give me a clue? but the log just says "ERROR (null), (null)"

any thoughts

Are you sure `context` is non-nil? – James Huddleston Nov 09 '10 at 19:18 — James Huddleston, Nov 09 '10 at 19:18

score 8 · Answer 1 · answered Oct 23 '11 at 12:11

8

I lived your pain and end up surviving. ;)

After long debugging time I realized in custom object validation method, in some cases I was returning NO and not initializing an error.

If you have this problem check validation object methods. That probably was your problem as well.

answered Oct 23 '11 at 12:11

C. Miranda

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1
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That may not have been the original poster's problem, but this is exactly what happened to me. Thanks! Seems like Core Data should throw an exception rather than contradict the NSManagedObjectContext documentation -- I should file a bug. – Alex Michaud Sep 19 '12 at 20:12
This deserves 10 *up* votes. This saved me hours of hair pulling, I'm sure! Agreed, it's probably not the original problem, but it certainly occurs with the exact same symptoms. – David Hunt Jan 09 '13 at 21:18
Oh my God! I'd spend hours to figure this out. Thanks! – Rudolf Adamkovič May 03 '13 at 15:15
Thanks! Also spend hours on it... until finding your hint. – Holtwick Feb 01 '14 at 13:18

score 7 · Accepted Answer · answered Nov 09 '10 at 20:42

7

Only way I can see that situation happening is if you are passing in a nil context. I would put a logic bomb at the top of that class method to guard against that.

Well, actually, I wouldn't create a class method for this small amount of code; but the point still stands. Check for a nil context.

answered Nov 09 '10 at 20:42

Marcus S. Zarra

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the context is not nil, i know this for sure – creativeKoder Nov 09 '10 at 21:53
i am how ever passing the context around, it starts in the app delegate and I pass it around from there, could that have anything to do with it. – creativeKoder Nov 09 '10 at 21:56
It may be getting released somewhere, or not retained? Have it spit out the current `[context retainCount]` with a `nil` check. It never hurts to check. – Stephen Furlani Nov 10 '10 at 13:54
never use retainCount, ever. Do an NSAssert check against nil at the top of the method. – Marcus S. Zarra Nov 10 '10 at 15:29
The context being nil was exactly my problem, thanks for the tip! – Chad Schultz Sep 12 '12 at 21:08

score 1 · Answer 3 · answered Dec 18 '13 at 18:31

This is a really old thread, but hopefully my response helps someone who finds this on Google like I did. I was running into this same problem and none of these answers were my problem; it turns out I made the very boneheaded, silly mistake of not deleting/reinstalling the app when I changed the data model, so the save was failing without an error. Check to make sure you don't do the same thing! :)

score 0 · Answer 4 · edited Oct 26 '12 at 09:24

0

I happened to meet this problem, and after long time debug I found it's because of a duplicate declaration of the NSError* error, may you had another NSError* error in the outer scope, like:

NSError* error = nil;

// some code

if (!error)
{
    NSError* error = nil;

    // your code
}

Then the error will be nil although in fact there is an exception.

edited Oct 26 '12 at 09:24

rdurand

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answered Apr 30 '12 at 05:53

shicong zhao

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2

score 0 · Answer 5 · answered Nov 09 '10 at 20:15

0

Uhm, I'm not sure %@ will cause the error to go verbose. [error localizedDescription] ?

answered Nov 09 '10 at 20:15

Stephen Furlani

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i have used both, [error userInfo] and [error localizedDescription], same thing error (null), (null) – creativeKoder Nov 09 '10 at 21:51

managedObjectContext save fails with error being null

5 Answers5