Unreal Engine Issues
Unreal Engine Issues
Imported heightmaps with 2x2 sections crash editor
UE - LD & Modeling - Terrain - Landscape - Jul 18, 2016Importing a heightmap with 2x2 segments seems to cause the editor to crash in 3 different instances: 1. Importing the same 2x2 segment landscape a second time after deleting the first instance 2. ...
[CrashReport] UE4Editor_Engine!UAnimMontage::IsValidAdditive() [animmontage.cpp:702]
OLD - Anim - May 19, 2016Error message: Stack overflow - code c00000fd (first/second chance not available) Source Context: 687 if (SyncGroup != NAME_None) 688 { 689 CollectMarkers(); 690 ...
[Gauntlet] TestExecutor does not clean up or release devices when a test's StartTest returns false, causing device starvation or a deadlock with -NoTimeout
UE - QA - Tooling - Oct 21, 2026Summary When UnrealTestNode.StartTest returns false (or throws), TestExecutor.ExecuteTests moves the test straight to CompletedTests. It never calls CleanupTest or StopTest on the node, so the device ...
HZB Occlusion causes large stalls on the render thread
UE - Rendering - RHI - Oct 7, 2025HZB Occlusion causes large stalls (greater than 5ms seen) on the render thread due to an RHI flush. This is caused by the following code in FDynamicRHI::RHIMapStagingSurface_RenderThread which force ...
Form Extended Structures will only destroy one mesh but not any attached
UE - Simulation - Physics - Destruction - Nov 28, 2014DESCRIPTION: While using form extended structures enabled for a Destruction mesh one of the meshes will be able to be damaged while any others attached will not fracture or damage at all. For exam ...
Actors in sublevels do not replicate to Clients after Seamless ServerTravel
UE - Networking - Dec 9, 2015Actors in sublevels do not replicate to Clients after Seamless ServerTravel. The user reporting this noted that "[...] UNetDriver::IsLevelInitializedForActor() keeps returning false even when the ac ...
[Interchange] Crash on asset re-import
zComponent - Archive - Feb 7, 2025We've started seeing a crash in editor when re-importing one of our assets. <pre class="ql-syntax">Assertion failed: (Index >= 0) & (Index < ArrayNum) [Link Removed] [Line: 783] Array index out of ...
Substrate Single Layer Water material fails to compile in blendable Gbuffer mode when using the Single Layer Water BSDF node
UE - Graphics Tools - Terrain - Water - Jun 16, 2026When using Substrate in Blendable GBuffer mode, a material with the single layer water BSDF node produces a shader compiler error : MaterialEditorStats: Error: [SM6] Shader debug info dumped to: "\ ...
GeometryCache: data race between FGeometryCacheSceneProxy::CreateHitProxies and the render-thread FrameUpdate enqueued by the proxy constructor
UE - Rendering - Architecture - Oct 13, 2026Symptom An intermittent ensureMsgf fires in the editor when a level contains a UGeometryCacheComponent: Array has changed during ranged-for iteration! (TArray ranged-for iterator check, Array.h). T ...
Capsule component Shape values can be glitched inside of Actor class bp
UE - Gameplay - Components - Oct 29, 2015Capsule component Shape values can be glitched inside of Actor class bp This effects 4.9.2 and 4.10 Preview 3, however it is working properly in 4.11-2736016 User Description: Alright, so the Cap ...