Description

This is a common crash in the 4.16 and 4.17 releases.

User Descriptions

  • Writing a custom component in C++. Hotcompiled it through VS2017. Had the BP editor open with a class derived from that component. Hit Compile in the BP editor, goodbye Unreal!

Source Context

 278       	// As DEFAULT_ALIGNMENT is defined to 0 now, I changed that to the original numerical value here
  279       	const int32 AlignmentCheck = MIN_ALIGNMENT - 1;
  280       
  281       	// Check 'this' pointer before trying to access any of the Object's members
  282       	if ((this == nullptr) || (UPTRINT)this < 0x100)
  283       	{
  284       		UE_LOG(LogUObjectBase, Error, TEXT("\'this\' pointer is invalid."));
  285       		return false;
  286       	}
  287       	if ((UPTRINT)this & AlignmentCheck)
  288       	{
  289       		UE_LOG(LogUObjectBase, Error, TEXT("\'this\' pointer is misaligned."));
  290       		return false;
  291       	}
  292 ***** 	if (*(void**)this == nullptr)
  293       	{
  294       		UE_LOG(LogUObjectBase, Error, TEXT("Virtual functions table is invalid."));
  295       		return false;
  296       	}
Steps to Reproduce

repro steps currently unknown

Callstack
Access violation - code c0000005 (first/second chance not available)

UE4Editor_CoreUObject!UObjectBase::IsValidLowLevelFast() [uobjectbase.cpp:294]
UE4Editor_CoreUObject!TFastReferenceCollector<1,FGCReferenceProcessor<1>,FGCCollector<1>,FGCArrayPool,0>::ProcessObjectArray() [fastreferencecollector.h:614]
UE4Editor_CoreUObject!TFastReferenceCollector<1,FGCReferenceProcessor<1>,FGCCollector<1>,FGCArrayPool,0>::FCollectorTaskQueue::DoTask() [fastreferencecollector.h:299]
UE4Editor_CoreUObject!TGraphTask<TFastReferenceCollector<1,FGCReferenceProcessor<1>,FGCCollector<1>,FGCArrayPool,0>::FCollectorTaskProcessorTask>::ExecuteTask() [taskgraphinterfaces.h:784]
UE4Editor_Core!FTaskThreadAnyThread::ProcessTasks() [taskgraph.cpp:907]
UE4Editor_Core!FTaskThreadAnyThread::ProcessTasksUntilQuit() [taskgraph.cpp:785]
UE4Editor_Core!FTaskThreadBase::Run() [taskgraph.cpp:501]
UE4Editor_Core!FRunnableThreadWin::Run() [windowsrunnablethread.cpp:76]

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Unresolved
ComponentCore
Affects Versions4.164.174.204.214.22
CreatedAug 22, 2017
ResolvedMar 28, 2018
UpdatedAug 2, 2019