This is a top 10 crash affecting many users. It is believed it may be related to the auto listen / reimport feature.
The callstack shares similarities to past tickets, such as:
In submitted logs, the following ensure frequently appears:
Ensure condition failed: false [File:D:\Build\++UE4+Release-4.15+Compile\Sync\Engine\Source\Runtime\CoreUObject\Private\Misc\PackageName.cpp] [Line: 650] Illegal call to DoesPackageExist: '/Game/ThirdPersonBP/Erika_Archer_with_bow_arrow.fbm/Arrow_DIFF' is not a standard unreal filename or a long path name. Reason: Path should be no less than 4 characters long.
User Descriptions:
repro steps currently unknown
Assertion failed: GetOuter()==NULL [File:D:\Build++UE4+Release-4.15+Compile\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Package.cpp|file:///D:/Build++UE4+Release-4.15+CompileSyncEngineSourceRuntimeCoreUObjectPrivateUObjectPackage.cpp] [Line: 157] UE4Editor_Core!FText::IsEmpty() text.cpp:248 UE4Editor_Core!FSlowTask::GetCurrentMessage() slowtask.cpp:102 UE4Editor_UnrealEd!SSlowTaskWidget::GetProgressText() feedbackcontexteditor.cpp:307 UE4Editor_UnrealEd!SSlowTaskWidget::GetMainTextFont() feedbackcontexteditor.cpp:261 UE4Editor_UnrealEd!TMemberFunctionCaller<SSlowTaskWidget,FSlateFontInfo() delegateinstanceinterface.h:165 UE4Editor_UnrealEd!TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<TMemberFunctionCaller<SSlowTaskWidget,FSlateFontInfo() tuple.h:134 UE4Editor_UnrealEd!TBaseSPMethodDelegateInstance<1,SSlowTaskWidget,0,FSlateFontInfo __cdecl() delegateinstancesimpl.h:327 UE4Editor_Slate!TBaseDelegate<FSlateFontInfo>::Execute() delegatesignatureimpl.inl:537 UE4Editor_Slate!TAttribute<FSlateFontInfo>::Get() attribute.h:137 UE4Editor_Slate!STextBlock::GetFont() stextblock.cpp:56 UE4Editor_Slate!STextBlock::GetComputedTextStyle() stextblock.cpp:305 UE4Editor_Slate!STextBlock::ComputeDesiredSize() stextblock.cpp:177 UE4Editor_SlateCore!SWidget::CacheDesiredSize() swidget.cpp:485 UE4Editor_SlateCore!SWidget::SlatePrepass() swidget.cpp:473 UE4Editor_SlateCore!SWidget::SlatePrepass() swidget.cpp:473 UE4Editor_SlateCore!SWidget::SlatePrepass() swidget.cpp:473 UE4Editor_SlateCore!SWidget::SlatePrepass() swidget.cpp:473 UE4Editor_SlateCore!SWidget::SlatePrepass() swidget.cpp:473 UE4Editor_SlateCore!SWidget::SlatePrepass() swidget.cpp:473 UE4Editor_SlateCore!SWidget::SlatePrepass() swidget.cpp:473 UE4Editor_Slate!PrepassWindowAndChildren() slateapplication.cpp:1268 UE4Editor_Slate!FSlateApplication::DrawPrepass() slateapplication.cpp:1292 UE4Editor_Slate!FSlateApplication::PrivateDrawWindows() slateapplication.cpp:1358 UE4Editor_Slate!FSlateApplication::DrawWindows() slateapplication.cpp:1115 UE4Editor_Slate!FSlateApplication::TickApplication() slateapplication.cpp:1720 UE4Editor_Slate!FSlateApplication::Tick() slateapplication.cpp:1512 UE4Editor!FEngineLoop::Tick() launchengineloop.cpp:3086 UE4Editor!GuardedMain() launch.cpp:166 UE4Editor!GuardedMainWrapper() launchwindows.cpp:134 UE4Editor!WinMain() launchwindows.cpp:210 UE4Editor!__scrt_common_main_seh() exe_common.inl:264 kernel32!BaseThreadInitThunk() ntdll!RtlUserThreadStart()
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-44071 in the post.