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Crash with skeletal mesh in 4.21


I get a crash with a specific skeletal mesh after upgrading to 4.21 from 4.19. However, my colleagues does not have this crash. We are using exactly the same versions of all software (including drivers), however our hardware differs. If I hide the mesh, I do not get this crash. We use the distributed version of the engine.

Any ideas what the problem might be or should this be reported as a bug?

 Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Build\++UE4\Sync\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 611] Array index out of bounds: 4 from an array of size 1
 UE4Editor_Core!FDebug::AssertFailed() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:417]
 UE4Editor_Engine!FGPUSkinCacheEntry::SetupSection() [d:\build\++ue4\sync\engine\source\runtime\engine\private\gpuskincache.cpp:304]
 UE4Editor_Engine!FGPUSkinCache::ProcessEntry() [d:\build\++ue4\sync\engine\source\runtime\engine\private\gpuskincache.cpp:1028]
 UE4Editor_Engine!FSkeletalMeshObjectGPUSkin::ProcessUpdatedDynamicData() [d:\build\++ue4\sync\engine\source\runtime\engine\private\skeletalrendergpuskin.cpp:480]
 UE4Editor_Engine!FSkeletalMeshObjectGPUSkin::UpdateDynamicData_RenderThread() [d:\build\++ue4\sync\engine\source\runtime\engine\private\skeletalrendergpuskin.cpp:312]
 UE4Editor_Engine!<lambda_329b6a51d194e26c00f4cb59ce3bbf32>::operator()() [d:\build\++ue4\sync\engine\source\runtime\engine\private\skeletalrendergpuskin.cpp:274]
 UE4Editor_Engine!TGraphTask<TEnqueueUniqueRenderCommandType<`FSkeletalMeshObjectGPUSkin::Update'::`2'::SkelMeshObjectUpdateDataCommandName,<lambda_329b6a51d194e26c00f4cb59ce3bbf32> > >::ExecuteTask() [d:\build\++ue4\sync\engine\source\runtime\core\public\async\taskgraphinterfaces.h:829]
 UE4Editor_Core!FNamedTaskThread::ProcessTasksNamedThread() [d:\build\++ue4\sync\engine\source\runtime\core\private\async\taskgraph.cpp:679]
 UE4Editor_Core!FNamedTaskThread::ProcessTasksUntilQuit() [d:\build\++ue4\sync\engine\source\runtime\core\private\async\taskgraph.cpp:575]
 UE4Editor_RenderCore!RenderingThreadMain() [d:\build\++ue4\sync\engine\source\runtime\rendercore\private\renderingthread.cpp:333]
 UE4Editor_RenderCore!FRenderingThread::Run() [d:\build\++ue4\sync\engine\source\runtime\rendercore\private\renderingthread.cpp:467]
 UE4Editor_Core!FRunnableThreadWin::Run() [d:\build\++ue4\sync\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:76]

Thanks in advance, any help is appreciated!


I discovered that after disabling cloth simulation the crash disappears. Unfortunately, so does the cloth simulation.

Product Version: UE 4.21
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asked Nov 30 '18 at 01:44 PM in Bug Reports

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avatar image Jeff A ♦♦ STAFF Nov 30 '18 at 04:22 PM


We've recently made a switch to a new bug reporting method using a more structured form. Please visit the link below for more details and report the issue using the new Bug Submission Form. Feel free to continue to use this thread for community discussion around the issue.



avatar image undercover Mar 07 '19 at 03:05 PM

Re-importing the problematic meshes solved the problem!

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