CoreData: error: NULL _cd_rawData but the object is not being turned into a fault

Question

I occasionally get this error when saving to core data. I cannot manage to recreate it.

Does anyone have any experience with this error;

CoreData: error: NULL _cd_rawData but the object is not being turned into a fault

?

Are you using multi threading? If yes, make sure that saving context should be done on Main Thread — Sanjeev Rao, Feb 10 '12 at 09:06
Yes I am. But im working in another context and merge the changes in the main thread. — johan, Feb 10 '12 at 09:21
Hi, can anyone explain why this error only happens occasionally? — iamdavidlam, Feb 13 '15 at 10:00
As a general approach to learning more about the topic and ways to prevent such issues I would recommend the following Stanford lecture: https://www.youtube.com/watch?v=whF63GTaW1w — Philip De Vries, Jun 06 '18 at 17:41

score 57 · Answer 1 · edited Jun 20 '20 at 09:12

57

Reason:

This happens when the object's context does not belong to the current thread. One of many ways that mistake can manifest itself.

When the crash occurs do the following:

Check the thread in which the crash occured (Xcode > Debug Navigator)
On the console print, the concurrency type of the NSManagedObjectContext
If the concurrency type is mainQueueConcurrencyType then it needs to be on the main thread otherwise on the background threads.

p context.concurrencyType

In the sample command above the NSManagedObjectContext was stored in the variable context

(NSManagedObjectContextConcurrencyType) $R4 = mainQueueConcurrencyType

edited Jun 20 '20 at 09:12

Community

answered Aug 29 '13 at 21:29

Neal Ehardt

2

Yes this was exactly my case. This error is basically because of accessing the main MOC from the background thread. – Roohul Dec 26 '16 at 07:48
1

Is there any solution for this? – Kirti Nikam Jul 12 '17 at 11:10
3

If you need to access the database from a background thread, use that thread to create a new MOC, then use it to create, query, mutate, save, etc. [MagicalRecord](https://github.com/magicalpanda/MagicalRecord) was very helpful for my app. – Neal Ehardt Jul 14 '17 at 22:46
1

In my case, It was already on the background thread but the frequent switching from the backgrounf thread to main thread causes this error and a crash – Vin Feb 28 '19 at 07:44

score 14 · Accepted Answer · edited Nov 27 '18 at 16:12

14

edited Nov 27 '18 at 16:12

Tom Harrington

answered Feb 10 '12 at 10:19

iamsult

Link is not active anymore, solution not visible! – matzino Nov 26 '18 at 10:04
Answer edited to put an active link to the same content. – Tom Harrington Nov 28 '18 at 15:57

score 1 · Answer 3 · edited Nov 16 '17 at 18:14

1

I found the same problem when I tried to read (access) data from a Coredata Store in other thread (not main).

You can solve this problem by following this suggestion from this link:
Core Data and threads / Grand Central Dispatch

edited Nov 16 '17 at 18:14

lewis

answered Jun 01 '15 at 20:44

Ohmy

That thread has 6 answers; can you be more specific about what you found in that thread that was helpful? – ConfusionTowers Sep 28 '18 at 20:09