Fatal Exception: NSInternalInconsistencyException how to find offending code?

Question

I've this random crash in live app. I know how to fix it. I want to know how to find out offending code as the crashlytics log doesn't show any code in my app. Is this crashlytics crash?

Since it's random crash I can't debug it.

Any pointer to find out offending code will be appreciated.

Fatal Exception: NSInternalInconsistencyException
Modifications to the layout engine must not be performed from a background thread after it has been accessed from the main thread.


Fatal Exception: NSInternalInconsistencyException
0  CoreFoundation                 0x196676a48 __exceptionPreprocess
1  libobjc.A.dylib                0x19639dfa4 objc_exception_throw
2  Foundation                     0x196b4cf08 -[NSISEngine tryToOptimizeReturningMutuallyExclusiveConstraints]
3  Foundation                     0x196957d34 -[NSISEngine _optimizeWithoutRebuilding]
4  Foundation                     0x196957c4c -[NSISEngine optimize]
5  Foundation                     0x1969578c0 -[NSISEngine performPendingChangeNotifications]
6  UIKitCore                      0x19ab6c9e0 -[UIView(Hierarchy) layoutSubviews]
7  UIKitCore                      0x19ab7f3d0 -[UIView(CALayerDelegate) layoutSublayersOfLayer:]
8  QuartzCore                     0x19d0e27dc -[CALayer layoutSublayers]
9  QuartzCore                     0x19d0e8958 CA::Layer::layout_if_needed(CA::Transaction*)
10 QuartzCore                     0x19d0f3578 CA::Layer::layout_and_display_if_needed(CA::Transaction*)
11 QuartzCore                     0x19d03bf1c CA::Context::commit_transaction(CA::Transaction*, double)
12 QuartzCore                     0x19d065c08 CA::Transaction::commit()
13 QuartzCore                     0x19d066b8c CA::Transaction::release_thread(void*)
14 libsystem_pthread.dylib        0x196394fb0 _pthread_tsd_cleanup
15 libsystem_pthread.dylib        0x196391de8 _pthread_exit
16 libsystem_pthread.dylib        0x196392e7c _pthread_wqthread_legacy_worker_wrap
17 libsystem_pthread.dylib        0x196392c18 _pthread_wqthread
18 libsystem_pthread.dylib        0x196395760 start_wqthread


Crashed: com.twitter.crashlytics.ios.exception
EXC_BREAKPOINT 0x00000001962dd8e0
Crashed: com.twitter.crashlytics.ios.exception
0  myApp                0x10101f028 CLSProcessRecordAllThreads + 376 (CLSProcess.c:376)
1  myApp                0x10101f410 CLSProcessRecordAllThreads + 407 (CLSProcess.c:407)
2  myApp                0x10100f114 CLSHandler + 26 (CLSHandler.m:26)
3  myApp                0x10101d63c __CLSExceptionRecord_block_invoke + 198 (CLSException.mm:198)
4  libdispatch.dylib              0x196343184 _dispatch_client_callout + 16
5  libdispatch.dylib              0x1962f5c04 _dispatch_lane_barrier_sync_invoke_and_complete + 56
6  myApp                0x10101d0e4 CLSExceptionRecord + 205 (CLSException.mm:205)
7  myApp                0x10101cf18 CLSExceptionRecordNSException + 102 (CLSException.mm:102)
8  myApp                0x10101cb3c CLSTerminateHandler() + 258 (CLSException.mm:258)
9  libc++abi.dylib                0x196443304 std::__terminate(void (*)()) + 16
10 libc++abi.dylib                0x196442c58 __cxa_get_exception_ptr + 30
11 libc++abi.dylib                0x196442c18 __cxxabiv1::exception_cleanup_func(_Unwind_Reason_Code, _Unwind_Exception*) + 122
12 libobjc.A.dylib                0x19639e0d0 _objc_exception_destructor(void*) + 354
13 Foundation                     0x196b4cf08 -[NSISEngine tryToOptimizeReturningMutuallyExclusiveConstraints] + 318
14 Foundation                     0x196957d34 -[NSISEngine _optimizeWithoutRebuilding] + 68
15 Foundation                     0x196957c4c -[NSISEngine optimize] + 112
16 Foundation                     0x1969578c0 -[NSISEngine performPendingChangeNotifications] + 112
17 UIKitCore                      0x19ab6c9e0 -[UIView(Hierarchy) layoutSubviews] + 308
18 UIKitCore                      0x19ab7f3d0 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2140
19 QuartzCore                     0x19d0e27dc -[CALayer layoutSublayers] + 284
20 QuartzCore                     0x19d0e8958 CA::Layer::layout_if_needed(CA::Transaction*) + 480
21 QuartzCore                     0x19d0f3578 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 136
22 QuartzCore                     0x19d03bf1c CA::Context::commit_transaction(CA::Transaction*, double) + 304
23 QuartzCore                     0x19d065c08 CA::Transaction::commit() + 676
24 QuartzCore                     0x19d066b8c CA::Transaction::release_thread(void*) + 228
25 libsystem_pthread.dylib        0x196394fb0 _pthread_tsd_cleanup + 580
26 libsystem_pthread.dylib        0x196391de8 _pthread_exit + 80
27 libsystem_pthread.dylib        0x196392e7c _pthread_wqthread_legacy_worker_wrap + 94
28 libsystem_pthread.dylib        0x196392c18 _pthread_wqthread + 420
29 libsystem_pthread.dylib        0x196395760 start_wqthread + 8

Answer 1

I've seen a similar stacktrace on crashes that come from Ads SDKs. Do you have and ads in your app? or WKWebviews? If yes, try to disable them and check if the crash still happens.