Crash when moving actors between levels

Development Platform & Builds
, , , ,
1

Hello,

We are experiencing crashes when moving actors between levels. While certain actors can be moved, others crashes engine, even including different instances of same actor.

Which instances that causes engine to crash appears to be completely random, but are always same. It ranges from instances that were placed months ago to instances that were placed as late as yesterday.

Crash report (dump):

UE4Editor_Engine!UStaticMeshComponent::DoCustomNavigableGeometryExport() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\components\staticmeshcomponent.cpp:1653]
UE4Editor_Engine!FRecastNavMeshGenerator::ExportComponentGeometry() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\recastnavmeshgenerator.cpp:4034]
UE4Editor_Engine!TBaseStaticDelegateInstance::ExecuteIfSafe() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:921]
UE4Editor_Engine!FNavigationOctree::AddNode() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\navigationoctree.cpp:109]
UE4Editor_Engine!UNavigationSystem::AddElementToNavOctree() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\navigationsystem.cpp:2229]
UE4Editor_Engine!UNavigationSystem::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\ai\navigation\navigationsystem.cpp:722]
UE4Editor_Engine!UWorld::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\engine\private\leveltick.cpp:1152]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\editor\unrealed\private\editorengine.cpp:1134]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\editor\unrealed\private\unrealedengine.cpp:366]
UE4Editor!FEngineLoop::Tick() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\launchengineloop.cpp:2359]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\launch.cpp:142]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]

2

I seem to have found a workaround for this issue. Renaming a “faulty” instance lets me move it to another level. For instance, adding a “0” to end of name fixes it.

Another thing that makes this an odd issue is that it now appears pretty predictable in some cases. For instance, ‘Object_01’ will crash engine, while other instances, named ‘Object_01_thin’ or ‘Object_01_flattened’, or any other names like that, will not. same goes for ‘Object_02’, ‘Object_03’, and so on. Note that all these names are default names they get when they are placed into world.

Although I now have a workaround, it is still a pretty major issue though.

3

Hi Zaldir,

Can you try reproducing this in a new project, and giving us some step-by-step instruction so we can attempt it here? Thanks!

4

Hi Zaldir,

Actually, I just found a similar issue in our database with same crash call stack (UE-15110). It appears to be fixed in our internal build, and fix should be included in a future release (probably 4.9). If you would like to verify, fix should also be in Master branch on GitHub. In meantime, I’m glad you’ve got a workaround. Thanks for report!

5

Cheers! We’ll keep working around it until 4.9 then. Thanks for quick response!