After importing a mesh without any materials assigned, if you add a material slot and save the material. Reimporting this mesh will cause a crash.
The only way to avoid this crash is to import a mesh with materials already assigned.
The reason this doesn't reproduce in 4.14.1 is because the test asset is assigned a material slot automatically. This prevents the step of adding a material slot which is crucial to reproducing this crash.
Frequency: 10/10 repro
REGRESSION?
Yes
Can't Reproduce - Internal Binary 4.14.1 CL 3224400
Reproduced - Launcher Binary 4.14.3 CL 3249277
RESULT
The engine crashes while attempting reimport.
EXPECTED
The mesh reimports without any material slots just like it's initial import.
UE4Editor_UnrealEd!RestoreExistingMeshData() staticmeshedit.cpp:1180 UE4Editor_UnrealEd!UnFbx::FFbxImporter::ReimportStaticMesh() fbxstaticmeshimport.cpp:984 UE4Editor_UnrealEd!UReimportFbxStaticMeshFactory::Reimport() editorfactories.cpp:5763 UE4Editor_UnrealEd!FReimportManager::Reimport() editor.cpp:319 UE4Editor_UnrealEd!FReimportManager::ReimportMultiple() editor.cpp:504 UE4Editor_UnrealEd!FReimportManager::ValidateAllSourceFileAndReimport() editor.cpp:487 UE4Editor_ContentBrowser!FAssetContextMenu::ExecuteReimport() assetcontextmenu.cpp:1355 UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,FAssetContextMenu,0,TTypeWrapper<void> __cdecl() delegateinstancesimpl.h:318 UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,FAssetContextMenu,0,void __cdecl() delegateinstancesimpl.h:424 UE4Editor_Slate!SMenuEntryBlock::OnClicked() smenuentryblock.cpp:1042 UE4Editor_Slate!SMenuEntryBlock::OnMenuItemButtonClicked() smenuentryblock.cpp:993 UE4Editor_Slate!TMemberFunctionCaller<SMenuEntryBlock,FReply() delegateinstanceinterface.h:161 UE4Editor_Slate!TTupleImpl<TIntegerSequence<unsigned int> >::ApplyAfter<TMemberFunctionCaller<SMenuEntryBlock,FReply() tuple.h:116 UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SMenuEntryBlock,0,FReply __cdecl() delegateinstancesimpl.h:318 UE4Editor_Slate!TBaseDelegate<FReply>::Execute() delegatesignatureimpl.inl:522 UE4Editor_Slate!SButton::OnMouseButtonUp() sbutton.cpp:275 UE4Editor_Slate!SMenuEntryButton::OnMouseButtonUp() smenuentryblock.cpp:391 UE4Editor_Slate!<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1>::operator() slateapplication.cpp:5010 UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1> >() slateapplication.cpp:215 UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() slateapplication.cpp:4999 UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() slateapplication.cpp:5462 UE4Editor_Slate!FSlateApplication::OnMouseUp() slateapplication.cpp:5439 UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() windowsapplication.cpp:1652 UE4Editor_Core!FWindowsApplication::DeferMessage() windowsapplication.cpp:2071 UE4Editor_Core!FWindowsApplication::ProcessMessage() windowsapplication.cpp:814 UE4Editor_Core!FWindowsApplication::AppWndProc() windowsapplication.cpp:678 user32!UserCallWinProcCheckWow() user32!DispatchMessageWorker() UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() windowsplatformmisc.cpp:951 UE4Editor!FEngineLoop::Tick() launchengineloop.cpp:2811 UE4Editor!GuardedMain() launch.cpp:152 UE4Editor!GuardedMainWrapper() launchwindows.cpp:126 UE4Editor!WinMain() launchwindows.cpp:202 UE4Editor!__scrt_common_main_seh() exe_common.inl:264 kernel32!BaseThreadInitThunk() ntdll!RtlUserThreadStart()
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