NSKeyValuePopPendingNotificationLocal Crash on iOS 13 and 14

Question

I am getting a crash on the live app I am working on and I can't seem to recreate or find the issue. This is the crash output:

`Crashed: NSOperationQueue 0x123e7d5c0 (QOS: UNSPECIFIED)
0  libobjc.A.dylib                0x184a52198 objc_release + 104
1  Foundation                     0x1850bd930 NSKeyValuePopPendingNotificationLocal + 60
2  Foundation                     0x1850bd8ac NSKeyValueDidChange.llvm.947807775919258276 + 364
3  Foundation                     0x1850bd2e0 -[NSObject(NSKeyValueObservingPrivate) _changeValueForKeys:count:maybeOldValuesDict:maybeNewValuesDict:usingBlock:] + 624
4  Foundation                     0x18500cb1c -[NSObject(NSKeyValueObservingPrivate) _changeValueForKey:key:key:usingBlock:] + 68
5  Foundation                     0x1850b8eb8 _NSSetLongLongValueAndNotify + 284
6  CFNetwork                      0x1880f4470 _CFNetworkHTTPConnectionCacheSetLimit + 205660
7  Foundation                     0x1850d5410 __NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 16
8  Foundation                     0x184fdf138 -[NSBlockOperation main] + 100
9  Foundation                     0x1850d7698 __NSOPERATION_IS_INVOKING_MAIN__ + 20
10 Foundation                     0x184fdedd0 -[NSOperation start] + 732
11 Foundation                     0x1850d8090 __NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 20
12 Foundation                     0x1850d7b5c __NSOQSchedule_f + 180
13 libdispatch.dylib              0x18498f7dc _dispatch_block_async_invoke2 + 104
14 libdispatch.dylib              0x1849dd184 _dispatch_client_callout + 16
15 libdispatch.dylib              0x184985a3c _dispatch_continuation_pop$VARIANT$mp + 412
16 libdispatch.dylib              0x184985190 _dispatch_async_redirect_invoke + 600
17 libdispatch.dylib              0x184991fa4 _dispatch_root_queue_drain + 376
18 libdispatch.dylib              0x184992770 _dispatch_worker_thread2 + 128
19 libsystem_pthread.dylib        0x184a2cb48 _pthread_wqthread + 212
20 libsystem_pthread.dylib        0x184a2f760 start_wqthread + 8`

Please help me to figure out this thing. Thanks

Answer 1

It is caused by FirebasePerformance v3.3.1 and XCode 12. Use 'FirebasePerformance', '3.3.0' should solve the problem.

After setting FirebasePerformance to v3.3.0, we did not see any NSKeyValuePopPendingNotificationLocal, AFURLSessionManager, NSKVODeallocate, CFDictionaryGetValue, NSKeyValueWillChange, [NSObject(NSKeyValueObservingPrivate) _changeValueForKeys:count:maybeOldValuesDict:maybeNewValuesDict:usingBlock:]... crashes anymore.

The crash-free percentage is recovered from 95% to 99.9%.