Description

This Mac crash originally occurred in 4.15 around March 2017, then decreased in frequency during 4.16 and 4.17. It may be starting to trend again in 4.18. There is one record of this occurring in 4.13 (in July 2017) and no records for 4.14.

According to logs, an Ensure occurs prior to the crash.

Ensure condition failed: Lhs.CurrentNum == Lhs.InitialNum [File:Runtime/Core/Public/Containers/Array.h] [Line: 206]

I've identified two different error messages that occur with this callstack.
1. SIGSEGV: invalid attempt to access memory at address 0x6f00000069
2. SIGBUS: invalid attempt to access memory at address 0x1709df4c0

User Descriptions

  • 1. Blueprint Editor editting a character blueprint 2. Add component, started searching for "Spring arm" but didn't select it 3. Used ctrl + right to switch to Desktop 2 on my Macbook 4. Used ctrl + left to come back to the Blueprint Editor

Callstack from Log

[2017.10.27-12.02.54:645][961]LogStaticLightingSystem: Running Lightmass w/ Mapping debug paddings DISABLED
[2017.10.27-12.02.54:657][961]Cmd: MAP CHECK DONTDISPLAYDIALOG
[2017.10.27-12.02.54:657][961]MapCheck: New page: Untitled_2 - Oct 28, 2017, 4:02:54 AM
[2017.10.27-12.02.54:658][961]MapCheck: Error: WorldSettings Maps need lighting rebuilt 
[2017.10.27-12.02.54:688][961]MapCheck: Map check complete: 1 Error(s), 0 Warning(s), took 30.612ms to complete.
[2017.10.27-12.02.54:689][961]LogEditorBuildUtils: Build time 0:00
[2017.10.27-12.03.00:130][100]LogStats: FPlatformStackWalk::StackWalkAndDump -  0.012 s
[2017.10.27-12.03.00:130][100]LogOutputDevice: Error: === Handled ensure: ===
[2017.10.27-12.03.00:131][100]LogOutputDevice: Error: 
[2017.10.27-12.03.00:131][100]LogOutputDevice: Error: Ensure condition failed: Lhs.CurrentNum == Lhs.InitialNum [File:Runtime/Core/Public/Containers/Array.h] [Line: 206]
[2017.10.27-12.03.00:131][100]LogOutputDevice: Error: Array has changed during ranged-for iteration!
[2017.10.27-12.03.00:131][100]LogOutputDevice: Error: Stack: 
[2017.10.27-12.03.00:131][100]LogOutputDevice: Error: [Callstack] 0x003d938d UE4Editor-Core.dylib!FDebug::OptionallyLogFormattedEnsureMessageReturningFalse(bool, char const*, char const*, int, wchar_t const*, ...)   [UnknownFile]) 
[2017.10.27-12.03.00:131][100]LogOutputDevice: Error: [Callstack] 0x06075d1e UE4Editor-Slate.dylib!PrepassWindowAndChildren(TSharedRef<SWindow, (ESPMode)0>)   [UnknownFile]) 
[2017.10.27-12.03.00:132][100]LogOutputDevice: Error: [Callstack] 0x0607515c UE4Editor-Slate.dylib!FSlateApplication::DrawPrepass(TSharedPtr<SWindow, (ESPMode)0>)   [UnknownFile]) 
[2017.10.27-12.03.00:132][100]LogOutputDevice: Error: [Callstack] 0x0607166d UE4Editor-Slate.dylib!FSlateApplication::PrivateDrawWindows(TSharedPtr<SWindow, (ESPMode)0>)   [UnknownFile]) 
[2017.10.27-12.03.00:132][100]LogOutputDevice: Error: [Callstack] 0x06071172 UE4Editor-Slate.dylib!FSlateApplication::DrawWindows()   [UnknownFile]) 
[2017.10.27-12.03.00:132][100]LogOutputDevice: Error: [Callstack] 0x0607a32d UE4Editor-Slate.dylib!FSlateApplication::TickApplication(ESlateTickType, float)   [UnknownFile]) 
[2017.10.27-12.03.00:132][100]LogOutputDevice: Error: [Callstack] 0x060782d6 UE4Editor-Slate.dylib!FSlateApplication::Tick(ESlateTickType)   [UnknownFile]) 
[2017.10.27-12.03.00:132][100]LogOutputDevice: Error: [Callstack] 0x0001ef9e UE4Editor!FEngineLoop::Tick()   [UnknownFile]) 
[2017.10.27-12.03.00:132][100]LogOutputDevice: Error: [Callstack] 0x00026e62 UE4Editor!GuardedMain(wchar_t const*)   [UnknownFile]) 
[2017.10.27-12.03.00:133][100]LogOutputDevice: Error: [Callstack] 0x00034500 UE4Editor!-[UE4AppDelegate runGameThread:]   [UnknownFile]) 
[2017.10.27-12.03.00:133][100]LogOutputDevice: Error: [Callstack] 0x00359137 UE4Editor-Core.dylib!-[FCocoaGameThread main]   [UnknownFile]) 
[2017.10.27-12.03.00:133][100]LogOutputDevice: Error: [Callstack] 0xbc4878ad Foundation!__NSThread__start__()   [UnknownFile]) 
[2017.10.27-12.03.00:133][100]LogOutputDevice: Error: [Callstack] 0x09bf8b90 libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
[2017.10.27-12.03.00:133][100]LogOutputDevice: Error: [Callstack] 0x09bf8adc libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
[2017.10.27-12.03.00:133][100]LogOutputDevice: Error: [Callstack] 0x09bf82c5 libsystem_pthread.dylib!thread_start()   [UnknownFile]) 
[2017.10.27-12.03.00:134][100]LogOutputDevice: Error: 
[2017.10.27-12.03.00:136][100]LogStats: SubmitErrorReport -  0.000 s
[2017.10.27-12.03.06:972][100]LogStats: SendNewReport -  6.836 s
[2017.10.27-12.03.06:972][100]LogStats: FDebug::EnsureFailed -  6.855 s
[2017.10.27-12.03.07:037][100]LogMac: === Critical error: ===
SIGSEGV: invalid attempt to access memory at address 0x6f00000069

[2017.10.27-12.03.07:037][100]LogMac: 
0x06075e31 UE4Editor-Slate.dylib!PrepassWindowAndChildren(TSharedRef<SWindow, (ESPMode)0>)   [UnknownFile]) 
0x0607515c UE4Editor-Slate.dylib!FSlateApplication::DrawPrepass(TSharedPtr<SWindow, (ESPMode)0>)   [UnknownFile]) 
0x0607166d UE4Editor-Slate.dylib!FSlateApplication::PrivateDrawWindows(TSharedPtr<SWindow, (ESPMode)0>)   [UnknownFile]) 
0x06071172 UE4Editor-Slate.dylib!FSlateApplication::DrawWindows()   [UnknownFile]) 
0x0607a32d UE4Editor-Slate.dylib!FSlateApplication::TickApplication(ESlateTickType, float)   [UnknownFile]) 
0x060782d6 UE4Editor-Slate.dylib!FSlateApplication::Tick(ESlateTickType)   [UnknownFile]) 
0x0001ef9e UE4Editor!FEngineLoop::Tick()   [UnknownFile]) 
0x00026e62 UE4Editor!GuardedMain(wchar_t const*)   [UnknownFile]) 
0x00034500 UE4Editor!-[UE4AppDelegate runGameThread:]   [UnknownFile]) 
0x00359137 UE4Editor-Core.dylib!-[FCocoaGameThread main]   [UnknownFile]) 
0xbc4878ad Foundation!__NSThread__start__()   [UnknownFile]) 
0x09bf8b90 libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
0x09bf8adc libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
0x09bf82c5 libsystem_pthread.dylib!thread_start()   [UnknownFile]) 
Steps to Reproduce

repro steps currently unknown. One user description describes the crash as occurring while working with the Blueprint editor

Callstack
BUS_ADRERR at 0x1709df4c0

???!Unknown()
UE4Editor-Slate.dylib!PrepassWindowAndChildren(TSharedRef<SWindow,()
UE4Editor-Slate.dylib!FSlateApplication::DrawPrepass(TSharedPtr<SWindow,()
UE4Editor-Slate.dylib!FSlateApplication::PrivateDrawWindows(TSharedPtr<SWindow,()
UE4Editor-Slate.dylib!FSlateApplication::DrawWindows()
UE4Editor-Slate.dylib!FSlateApplication::TickApplication()
UE4Editor-Slate.dylib!FSlateApplication::Tick()
UE4Editor!FEngineLoop::Tick()
UE4Editor!GuardedMain()
UE4Editor!<Unknown>
UE4Editor-Core.dylib!<Unknown>
Foundation!Unknown()
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>

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Fixed
ComponentPlatform - Mac
Affects Versions4.134.154.164.174.184.194.204.214.22
Target Fix4.22
Fix Commit4993210
Main Commit4993211
Release Commit5200920
CreatedOct 27, 2017
ResolvedFeb 14, 2019
UpdatedMar 8, 2019