Fatal Exception: realm::KeyNotFound in Realm notification listener thread #7704

bodnar-dan · 2022-03-17T14:20:58Z

How frequently does the bug occur?

Sometimes

Description

Since version 10.22.0, but it happens in 10.24.0 too, we started to see this crash for some users. It happens in random places.

For example:

Crashed: Realm notification listener
Fatal Exception: realm::KeyNotFound No object with key '99' in 'class_[OBJECT]'`

There's no stack trace for this crash.

The stracktrace below is what's happening on main queue, but like I said, it happens randomly... when we insert something or read something.

Stacktrace & log output

com.apple.main-thread
0   libsystem_kernel.dylib         0x2640 __psynch_mutexwait + 8
1   libsystem_pthread.dylib        0x23dc _pthread_mutex_firstfit_lock_wait + 84
2   libsystem_pthread.dylib        0x952c _pthread_mutex_firstfit_lock_slow + 248
3   libc++.1.dylib                 0xf15c std::__1::mutex::lock() + 16
4   Realm                          0x3957a4 realm::_impl::RealmCoordinator::register_notifier(std::__1::shared_ptr<realm::_impl::CollectionNotifier>) + 56
5   Realm                          0x3d2488 realm::Results::prepare_async(realm::util::TaggedBool<realm::ForCallback>) + 640
6   Realm                          0x3c94a0 realm::Results::ensure_up_to_date(realm::Results::EvaluateMode) + 416
7   Realm                          0x3c8dc0 realm::util::Optional<realm::Obj> realm::Results::try_get<realm::Obj>(unsigned long) + 48
8   Realm                          0x3c9174 realm::util::Optional<realm::Obj> realm::Results::first<realm::Obj>() + 68
9   Realm                          0x12ffe0 RLMAccessorContext realm::Results::dispatch<auto realm::Results::first<RLMAccessorContext>(RLMAccessorContext&)::'lambda'(RLMAccessorContext&)>(RLMAccessorContext&) const + 412
10  Realm                          0x12fe30 auto realm::Results::first<RLMAccessorContext>(RLMAccessorContext&) + 24
11  Realm                          0x12dbe8 -[RLMResults firstObject] + 48

Can you reproduce the bug?

Not yet

Reproduction Steps

We wren't able to reproduce and few users are affected, but it happens repetitively for them.

Version

10.24.0

What SDK flavour are you using?

Local Database only

Are you using encryption?

No, not using encryption

Platform OS and version(s)

iOS 15.3.1

Build environment

Xcode version: Xcide 13.2.1
Dependency manager and version: Carthage

The text was updated successfully, but these errors were encountered:

dianaafanador3 · 2022-03-21T08:02:04Z

Hi @bodnar-dan Seems like the stack trace is not related to the crash, so we can't diagnose why this is happening. We may need more info to reproduce this.
We do have a fix in our more recent release why fixes which may solve the issue
Application would sometimes crash with exceptions like 'KeyNotFound' or
assertion "has_refs()". Other issues indicating file corruption may also be
fixed by this. The one mentioned here is the one that lead to solving the
problem. Can you update to that version and check if this is still happening

bodnar-dan · 2022-03-25T09:29:47Z

Thank you, I will update and return with a feedback. I will also try to find more info about the crash.

bodnar-dan · 2022-04-12T09:00:40Z

I still see this in 10.25.0.
One thing worth mentioning, this crash is happening when iOS is bringing back the app from background to connect to our paired BLE device. We have this Background Mode enabled and by the nature of this capability, iOS brings back the app from background to allow operations on BLE devices. We have this enabled for a few years and this was not changed in the recent releases. Also this happens on various iOS versions, not only the latest one...

dianaafanador3 · 2022-09-12T12:38:34Z

@bodnar-dan Can I see a full stack trace for this crash, even though it seems like some realm related code is running in the main thread during the crash, the real crash is happening in the realm notification listener thread.

leemaguire · 2022-09-26T13:13:52Z

@bodnar-dan Can you provide the requested information so that we can investigate further?

bodnar-dan · 2022-09-26T13:36:11Z

@leemaguire sadly I don't have a stack trace of the crash. The crash is reported on the Firebase thread for a reason (I learned that this is a common issue). Maybe that's because often the crash is happening while the app is in background. Ofc, we're unable to reproduce it in any way.

We only have this (and similar), without additional information. What I can also tell, is that for a specific user, it's always the same key and the same object. So, 805 is not random.

Fatal Exception: realm::KeyNotFound
No object with key '805' in 'class_MyRealmObject'

And I guess the key here is not the primary key, because in our case, the primary key is a String. 805 from the app point of view, means nothing.

We have 3 different Realms in our app (on different modules). All 3 Realm notification listener threads are looking normal.

Realm notification listener
0  libsystem_kernel.dylib         0x2e18 kevent + 8
1  Realm                          0x3a8c68 realm::_impl::ExternalCommitHelper::listen() + 156
2  Realm                          0x3a8db8 void* std::__1::__thread_proxy<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct> >, realm::_impl::ExternalCommitHelper::ExternalCommitHelper(realm::_impl::RealmCoordinator&)::$_0> >(void*) + 52
3  libsystem_pthread.dylib        0x19ac _pthread_start + 148
4  libsystem_pthread.dylib        0xe68 thread_start + 8

All other threads are also not reporting any work.

This issue is not affecting a lot of users, but it's repetitive for them (once happening, it always happens).
In our latest version, in the realm migration block we emptied the data stored for these affected objects, so all users were starting from scratch. I was under the impression this was triggered by some bad data. However, the crash is still visible (I really can't tell if it's for the same users).
In the next version we'll rename the classes and basically let Realm recreate the structure, without migrating any data. Not sure if this is going to help... but it's worth trying.

mr-grey · 2022-11-11T09:38:45Z

found the same crash in Our project:
Fatal Exception: RLMException
No object with key '454' in 'class_RealmUser'

where...
class RealmUser: Object {
@persisted(primaryKey: true) var uuid = ""
..
}

it crashed on static Function
static func getByPrimaryKey(uuid: String, realm: Realm? = try? Realm()) -> RealmUser? {
guard let realm = realm else { return nil }
return realm.object(ofType: RealmUser.self, forPrimaryKey: uuid) <--- here
}

luckysmg · 2022-11-13T03:21:08Z

Found this crash too..

Fatal Exception: realm::KeyNotFound

starchey · 2023-01-03T14:14:24Z

We're running into this same exception/crash. We're using Realm 10.25.1. This happens rarely, but when it does happen, it is most often a case where we're in a write block trying to add/delete object A (object A contains a list property of object Bs), and the exception will be related to the primary key of object B.

Fatal Exception: RLMException
0  CoreFoundation                 0x99288 __exceptionPreprocess
1  libobjc.A.dylib                0x16744 objc_exception_throw
2  Our Project                   0x3bf80c RLMAccessorContext::createObject(objc_object*, realm::CreatePolicy, bool, realm::ObjKey) + 1097 (RLMAccessor.mm:1097)
3  Our Project                   0x3c8740 void realm::Object::set_property_value_impl<objc_object* __strong, RLMAccessorContext>(RLMAccessorContext&, realm::Property const&, objc_object* __strong, realm::CreatePolicy, bool) + 1125 (RLMAccessor.mm:1125)
4  Our Project                   0x3bfce8 realm::Object realm::Object::create<objc_object* __strong, RLMAccessorContext>(RLMAccessorContext&, std::__1::shared_ptr<realm::Realm> const&, realm::ObjectSchema const&, objc_object* __strong, realm::CreatePolicy, realm::ObjKey, realm::Obj*) + 355 (object_accessor.hpp:355)
5  Our Project                   0x3bf4a8 RLMAccessorContext::createObject(objc_object*, realm::CreatePolicy, bool, realm::ObjKey) + 1093 (RLMAccessor.mm:1093)
6  Our Project                   0x3c8740 void realm::Object::set_property_value_impl<objc_object* __strong, RLMAccessorContext>(RLMAccessorContext&, realm::Property const&, objc_object* __strong, realm::CreatePolicy, bool) + 1125 (RLMAccessor.mm:1125)
7  Our Project                   0x3bfce8 realm::Object realm::Object::create<objc_object* __strong, RLMAccessorContext>(RLMAccessorContext&, std::__1::shared_ptr<realm::Realm> const&, realm::ObjectSchema const&, objc_object* __strong, realm::CreatePolicy, realm::ObjKey, realm::Obj*) + 355 (object_accessor.hpp:355)
8  Our Project                   0x3bf4a8 RLMAccessorContext::createObject(objc_object*, realm::CreatePolicy, bool, realm::ObjKey) + 1093 (RLMAccessor.mm:1093)
9  Our Project                   0x408728 RLMAddObjectToRealm + 139 (RLMObjectStore.mm:139)
10 Our Project                   0x55be9c Realm.add<A>(_:update:) + 432 (Realm.swift:432)
11 Our Project                   0xd8b30 closure #2 in StoryRepository.cacheStories(stories:sectionIds:queueKey:deleteExisting:offset:realm:) + 521 (StoryRepository.swift:521)
12 Our Project                   0x6f754 thunk for @callee_guaranteed () -> (@error @owned Error) (<compiler-generated>)
13 Our Project                   0xdc4c8 partial apply for thunk for @callee_guaranteed () -> (@error @owned Error) (<compiler-generated>)
14 Our Project                   0x55b6b8 Realm.write<A>(withoutNotifying:_:) + 255 (Realm.swift:255)
15 Our Project                   0xd89c0 StoryRepository.cacheStories(stories:sectionIds:queueKey:deleteExisting:offset:realm:) + 516 (StoryRepository.swift:516)
16 Our Project                   0xd85e0 StoryRepository.insertStories(storyList:sectionIds:queueKey:deleteExisting:queue:offset:) + 492 (StoryRepository.swift:492)
17 Our Project                   0xd7ec8 closure #1 in closure #3 in StoryRepository.remoteStories(sectionInfos:sectionSource:queue:page:limit:offset:query:cachedStories:isNotPaginated:) + 391 (StoryRepository.swift:391)
18 Our Project                   0x6f754 thunk for @callee_guaranteed () -> (@error @owned Error) (<compiler-generated>)
19 Our Project                   0xdc4c8 partial apply for thunk for @callee_guaranteed () -> (@error @owned Error) (<compiler-generated>)
20 Our Project                   0xddc6c thunk for @callee_guaranteed () -> (@error @owned Error)partial apply
21 libswiftObjectiveC.dylib       0x1a10 autoreleasepool<A>(invoking:)
22 Our Project                   0xdd11c partial apply for closure #3 in StoryRepository.remoteStories(sectionInfos:sectionSource:queue:page:limit:offset:query:cachedStories:isNotPaginated:) (<compiler-generated>)
23 Our Project                   0x628ac8 closure #2 in ObservableType.do(onNext:afterNext:onError:afterError:onCompleted:afterCompleted:onSubscribe:onSubscribed:onDispose:) + 40 (Do.swift:40)
24 Our Project                   0x628b3c partial apply for closure #2 in ObservableType.do(onNext:afterNext:onError:afterError:onCompleted:afterCompleted:onSubscribe:onSubscribed:onDispose:) (<compiler-generated>)
25 Our Project                   0x629398 partial apply for closure #1 in ObservableType.do(onNext:afterNext:onError:afterError:onCompleted:afterCompleted:onSubscribe:onSubscribed:onDispose:)
26 Our Project                   0x628dcc DoSink.on(_:) + 66 (Do.swift:66)
27 Our Project                   0x628f90 protocol witness for ObserverType.on(_:) in conformance DoSink<A> (<compiler-generated>)
28 Our Project                   0x643444 ObserveOnSink.run(_:_:) + 133 (ObserveOn.swift:133)
29 Our Project                   0x6445ec partial apply for thunk for @escaping @callee_guaranteed (@unowned @callee_guaranteed () -> ()) -> () (<compiler-generated>)
30 Our Project                   0x6517f8 partial apply for thunk for @escaping @callee_guaranteed (@in_guaranteed A, @unowned @callee_guaranteed @substituted <A> (@in_guaranteed A) -> () for <A>) -> () (<compiler-generated>)
31 Our Project                   0x650f3c closure #1 in RecursiveImmediateScheduler.schedule(_:) (<compiler-generated>)
32 Our Project                   0x626ea0 partial apply for closure #1 in DispatchQueueConfiguration.schedule<A>(_:action:) + 27 (DispatchQueueConfiguration.swift:27)
33 Our Project                   0x27b4c thunk for @escaping @callee_guaranteed () -> () (<compiler-generated>)
34 libdispatch.dylib              0x1e6c _dispatch_call_block_and_release
35 libdispatch.dylib              0x3a30 _dispatch_client_callout
36 libdispatch.dylib              0xb124 _dispatch_lane_serial_drain
37 libdispatch.dylib              0xbc80 _dispatch_lane_invoke
38 libdispatch.dylib              0x16500 _dispatch_workloop_worker_thread
39 libsystem_pthread.dylib        0x10bc _pthread_wqthread
40 libsystem_pthread.dylib        0xe5c start_wqthread

dianaafanador3 · 2023-01-03T18:21:28Z

@starchey the stack trace doesn't mention the error on this issue, can you please attach a more detailed stack trace.

starchey · 2023-01-03T18:26:26Z

@starchey the stack trace doesn't mention the error on this issue, can you please attach a more detailed stack trace.

This is the full trace we're getting from Firebase. They all include Exception text like the following:

Fatal Exception: RLMException
No object with key '104' in 'class_OurObject'

zjh081777 · 2023-01-03T18:53:32Z

No object with key '513' in 'class_RealmString'
We had a lot of crash reports from production users lately and we are unable to repro. We are on 10.32.3.
The code is just trying to access [RLMResult count] property on a background thread


0    CoreFoundation                           0x18f181e88     _exceptionPreprocess + 164
1    libobjc.A.dylib                          0x1884bb8d8     objc_exception_throw + 59
2    Realm                                    0x1041dee9c     RLMThrowResultsError(NSString*) (RLMResults.mm:112)
3    Realm                                    0x1041df100     -[RLMResults count] (RLMResults.mm:149)
4    APP                  0x100f07ec8     buildCountMap #1 () in LMContactFilterButton.configureMenu() (LMContactFilterButton.swift:97)
5    APP                 0x100f079c4     closure #1 in LMContactFilterButton.configureMenu() (LMContactFilterButton.swift:72)
6    APP                  0x100cc0cbc     thunk for @escaping @callee_guaranteed () -> () (<compiler-generated>:0)
7    libdispatch.dylib                        0x1967504b4     _dispatch_call_block_and_release + 31
8    libdispatch.dylib                        0x196751fdc     _dispatch_client_callout + 19
9    libdispatch.dylib                        0x196759694     _dispatch_lane_serial_drain + 671
10   libdispatch.dylib                        0x19675a1e0     _dispatch_lane_invoke + 383
11   libdispatch.dylib                        0x196764e10     _dispatch_workloop_worker_thread + 651
12   libsystem_pthread.dylib                  0x1dc1d7df8     _pthread_wqthread + 287
13   libsystem_pthread.dylib                  0x1dc1d7b98     $start_wqthread + 7

Sample code:

let results = \* realm query to get RLMResults *\
if results.count > 0 { \\ crash on `results.count`!!
   ...
   }

dianaafanador3 · 2023-01-04T10:26:20Z

This issue may be caused by a file corruption that without access to a realm file it is really hard to diagnose. There is a fix which will be available in a future release which may fix this corruption issue realm/realm-core#5993
Be aware that the fix will not fix already corrupted files, but hopefully prevent creating corrupted files in the future..

starchey · 2023-01-04T16:26:46Z

This issue may be caused by a file corruption that without access to a realm file it is really hard to diagnose. There is a fix which will be available in a future release which may fix this corruption issue realm/realm-core#5993
Be aware that the fix will not fix already corrupted files, but hopefully prevent creating corrupted files in the future..

Thanks! Reading #8000 (comment), it sounds like this fix is included in v10.33.0, will update to that for our next release.

bodnar-dan · 2023-01-04T16:51:21Z

We still have the issue using Realm v10.33.0, but those could be users that have had their files corrupted when using the previous version.

@dianaafanador3 is there a way to catch file corruption exceptions so that we can handle them somehow, instead of crashing the app. Or is there any way for us to check the integrity of a Realm file?

dianaafanador3 · 2023-01-04T17:46:53Z

Actually for this particular case, if you catch the error KeyNotFound and ask the user or perform some actions after, which handle the issue somehow. (delete the realm file, for example)
In some other corruption cases, the assertion will make the app crash and there will be no way to handle the issue.

dianaafanador3 · 2023-02-10T19:05:59Z

@bodnar-dan can you update to our latest version 10.35.0, there are some fixes related to this in core, which may fix this issue.

andrefmsilva · 2023-03-09T13:42:39Z

Hi, I'm using the latest release and i still get this error.
I did some tests and i think it happens when we are observing changes for one specific key and then we delete the object and write new ones....

dianaafanador3 · 2023-04-11T17:01:52Z

Hi @andrefmsilva are you able to reproduce this. Can you please share a sample code with the reproduction you are describing?

andrefmsilva · 2023-04-11T17:07:10Z

Hi @dianaafanador3, after some debug i found the problem for my case.
My database was corrupted because i was deleting data using a predicate with properties that don't exist in the schema...

I don't know if it's the same problem for other users but the error after corruption was the same.

dianaafanador3 · 2023-04-11T17:11:38Z

mmm interesting. Have you tried our Swift Type Safe Query API https://www.mongodb.com/docs/realm/sdk/swift/crud/filter-data/#std-label-ios-realm-swift-query-api, which may prevent this issues to happen in the future.
This is probably something that should not be corrupting the data and an error should be throw in those cases. If you can provide a sample code, we can check it out and fix it if there is an issue.

andrefmsilva · 2023-04-12T14:45:35Z

I can't use the Query API with my current implementation because i have an abstraction layer that queries realm using some enum.

Basically each enum has cases to query a specific schema and knows how to create the Predicate (or NSCompoundPredicate) and NSSortDescriptor

dianaafanador3 · 2023-04-13T09:03:44Z

@andrefmsilva The weird thing is that if you use our API for filtering using a predicate with a wrong property name, for example
let objectsToDelete = results!.filter("nam == 'Something'")
should be getting an error like the following
"Invalid keypath 'nam': Property 'nam' not found in object of type 'Todo'", unless you are using another type of filtering that is not using our API.

dianaafanador3 · 2023-04-13T09:04:15Z

@bodnar-dan any updates from your side about this issue?

huutrung789 · 2023-05-10T03:51:09Z

Same issue with Realm version 10.38.0 - iPadOS 12.2.0

dianaafanador3 · 2023-05-25T11:55:33Z

HI @huutrung789 can you provide any more information about your issue, stack trace, sample code so we can reproduce this?.

nirinchev · 2024-02-07T16:01:29Z

We're closing this due to inactivity, but if you encounter a similar issue with the latest version of the Swift SDK, feel free to reopen.

bodnar-dan added the T-Bug label Mar 17, 2022

sync-by-unito bot added the Reproduction-Required label Jan 4, 2023

bmunkholm added Frequency:Sometimes labels Feb 12, 2023

bmunkholm removed Encryption:Off labels Feb 23, 2023

sync-by-unito bot assigned leemaguire Aug 22, 2023

sync-by-unito bot removed the T-Bug label Sep 12, 2023

nirinchev closed this as not planned Won't fix, can't repro, duplicate, stale Feb 7, 2024

github-actions bot locked as resolved and limited conversation to collaborators Mar 14, 2024

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Fatal Exception: realm::KeyNotFound in Realm notification listener thread #7704

Fatal Exception: realm::KeyNotFound in Realm notification listener thread #7704

bodnar-dan commented Mar 17, 2022 •

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dianaafanador3 commented Mar 21, 2022

bodnar-dan commented Mar 25, 2022

bodnar-dan commented Apr 12, 2022 •

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dianaafanador3 commented Sep 12, 2022

leemaguire commented Sep 26, 2022

bodnar-dan commented Sep 26, 2022 •

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mr-grey commented Nov 11, 2022

luckysmg commented Nov 13, 2022

starchey commented Jan 3, 2023

dianaafanador3 commented Jan 3, 2023

starchey commented Jan 3, 2023

zjh081777 commented Jan 3, 2023

dianaafanador3 commented Jan 4, 2023

starchey commented Jan 4, 2023

bodnar-dan commented Jan 4, 2023 •

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dianaafanador3 commented Jan 4, 2023

dianaafanador3 commented Feb 10, 2023

andrefmsilva commented Mar 9, 2023

dianaafanador3 commented Apr 11, 2023

andrefmsilva commented Apr 11, 2023

dianaafanador3 commented Apr 11, 2023 •

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andrefmsilva commented Apr 12, 2023

dianaafanador3 commented Apr 13, 2023

dianaafanador3 commented Apr 13, 2023

huutrung789 commented May 10, 2023

dianaafanador3 commented May 25, 2023

nirinchev commented Feb 7, 2024

Fatal Exception: realm::KeyNotFound in Realm notification listener thread #7704

Fatal Exception: realm::KeyNotFound in Realm notification listener thread #7704

Comments

bodnar-dan commented Mar 17, 2022 • edited Loading

How frequently does the bug occur?

Description

Stacktrace & log output

Can you reproduce the bug?

Reproduction Steps

Version

What SDK flavour are you using?

Are you using encryption?

Platform OS and version(s)

Build environment

dianaafanador3 commented Mar 21, 2022

bodnar-dan commented Mar 25, 2022

bodnar-dan commented Apr 12, 2022 • edited Loading

dianaafanador3 commented Sep 12, 2022

leemaguire commented Sep 26, 2022

bodnar-dan commented Sep 26, 2022 • edited Loading

mr-grey commented Nov 11, 2022

luckysmg commented Nov 13, 2022

starchey commented Jan 3, 2023

dianaafanador3 commented Jan 3, 2023

starchey commented Jan 3, 2023

zjh081777 commented Jan 3, 2023

dianaafanador3 commented Jan 4, 2023

starchey commented Jan 4, 2023

bodnar-dan commented Jan 4, 2023 • edited Loading

dianaafanador3 commented Jan 4, 2023

dianaafanador3 commented Feb 10, 2023

andrefmsilva commented Mar 9, 2023

dianaafanador3 commented Apr 11, 2023

andrefmsilva commented Apr 11, 2023

dianaafanador3 commented Apr 11, 2023 • edited Loading

andrefmsilva commented Apr 12, 2023

dianaafanador3 commented Apr 13, 2023

dianaafanador3 commented Apr 13, 2023

huutrung789 commented May 10, 2023

dianaafanador3 commented May 25, 2023

nirinchev commented Feb 7, 2024

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