This is a common crash affecting Mac users on 4.16, it has occurred since at least 4.14.
Users have not provided any descriptions.
repro steps currently unknown
Code in question involves handling the plugging in an iOS device while the editor is running. In the case it's crashing, the device info returned is invalid for some reason. Maybe the user pressed "don't trust"?
CoreFoundation!Unknown() UE4Editor-IOSTargetPlatform.dylib!FIOSDeviceHelper::DoDeviceConnect() MobileDevice!<Unknown> MobileDevice!<Unknown> CoreFoundation!Unknown() CoreFoundation!Unknown() CoreFoundation!Unknown() CoreFoundation!Unknown() UE4Editor-Core.dylib!PerformBlockOnThread(FCocoaRunLoopSource&, void() UE4Editor-Core.dylib!FMacApplication::UpdateScreensArray() UE4Editor-Core.dylib!FMacApplication::ProcessDeferredEvents() UE4Editor-Slate.dylib!FSlateApplication::TickPlatform() 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>
Callstack from Log
SIGSEGV: invalid attempt to access memory at address 0x0 LogMac: CFStringGetLength() Address = 0x7d83ff4a (filename not found) [in CoreFoundation] FIOSDeviceHelper::DoDeviceConnect(void*) Address = 0x4ceb656d (filename not found) [in UE4Editor-IOSTargetPlatform.dylib] _AMDDeviceAttachedCallbackv3() Address = 0x8d34c038 (filename not found) [in MobileDevice] _USBMuxCustomRunLoopSourcePerformCallback() Address = 0x8d2c903e (filename not found) [in MobileDevice] __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__() Address = 0x7d8d7321 (filename not found) [in CoreFoundation] __CFRunLoopDoSources0() Address = 0x7d8b821d (filename not found) [in CoreFoundation] __CFRunLoopRun() Address = 0x7d8b7716 (filename not found) [in CoreFoundation] CFRunLoopRunSpecific() Address = 0x7d8b7114 (filename not found) [in CoreFoundation] PerformBlockOnThread(FCocoaRunLoopSource&, void () block_pointer, NSArray*, NSString*, bool) Address = 0x31c2a5a (filename not found) [in UE4Editor-Core.dylib] FMacApplication::UpdateScreensArray() Address = 0x31cb219 (filename not found) [in UE4Editor-Core.dylib] FMacApplication::ProcessDeferredEvents(float) Address = 0x31cae90 (filename not found) [in UE4Editor-Core.dylib] FSlateApplication::TickPlatform(float) Address = 0x4aec9db (filename not found) [in UE4Editor-Slate.dylib] FSlateApplication::Tick(ESlateTickType) Address = 0x4aebe14 (filename not found) [in UE4Editor-Slate.dylib] FEngineLoop::Tick() Address = 0x2f1780c (filename not found) [in UE4Editor] GuardedMain(wchar_t const*) Address = 0x2f1de12 (filename not found) [in UE4Editor] -[UE4AppDelegate runGameThread:] Address = 0x2f2c01a (filename not found) [in UE4Editor] -[FCocoaGameThread main] Address = 0x31c2346 (filename not found) [in UE4Editor-Core.dylib] __NSThread__start__() Address = 0x7f2dab3d (filename not found) [in Foundation] _pthread_body() Address = 0x9324a93b (filename not found) [in libsystem_pthread.dylib] _pthread_body() Address = 0x9324a887 (filename not found) [in libsystem_pthread.dylib] thread_start() Address = 0x9324a08d (filename not found) [in libsystem_pthread.dylib]
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-47540 in the post.