_PFObjectIDFastHash64 Crash EXC_BAD_ACCESS KERN_INVALID_ADDRESS

Question

I keep getting reports of this crash via Crashlytics and I have no idea how to figure out what is going wrong, because the stack trace doesn't touch my code anywhere. What can I do? How do I find the source of the problem?

EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x0000000000000004
Crashed: com.apple.root.user-initiated-qos
0  CoreData                       0x1b85a87ac _PFObjectIDFastHash64 + 40
1  CoreFoundation                 0x1b254e4f8 __CFBasicHashRehash + 992
2  CoreFoundation                 0x1b2552414 CFBasicHashRemoveValue + 2384
3  CoreFoundation                 0x1b2469ec0 CFDictionaryRemoveValue + 236
4  CoreData                       0x1b84f51c0 -[NSManagedObjectContext(_NSInternalAdditions) _forgetObject:propagateToObjectStore:removeFromRegistry:] + 124
5  CoreData                       0x1b84d46ec -[_PFManagedObjectReferenceQueue _processReferenceQueue:] + 860
6  CoreData                       0x1b85a0734 -[_PFAutoreleasePoolThunk dealloc] + 48
7  libobjc.A.dylib                0x1c65bb81c AutoreleasePoolPage::releaseUntil(objc_object**) + 204
8  libobjc.A.dylib                0x1c65bb6e8 objc_autoreleasePoolPop + 212
9  libdispatch.dylib              0x1b2120aa4 _dispatch_last_resort_autorelease_pool_pop + 44
10 libdispatch.dylib              0x1b21313c8 _dispatch_root_queue_drain + 1064
11 libdispatch.dylib              0x1b21318e8 _dispatch_worker_thread2 + 116
12 libsystem_pthread.dylib        0x1f9a748cc _pthread_wqthread + 216
13 libsystem_pthread.dylib        0x1f9a7b77c start_wqthread + 8

Answer 1

It seems to be a multithreading error, "previously asymptomatic".

Add this argument to find out where exactly in your code :

-com.apple.CoreData.ConcurrencyDebug 1

It helps me a lot, I hope this will help you too.

Answer 2

We've started seeing this too in devices running iOS 14. Not touching any of our code either in main or background threads. Suspect we're potentially seeing an iOS 14 bug.

Suggest putting it in Apple Developer Forums.