Unreal Engine Issues
Unreal Engine Issues
[CrashReport] Crash on Mac - UE4Editor-SlateCore.dylib!SWindow::IsVisible()
UE - Platform - Apple - Jun 23, 2017This is a common crash on Mac in the 4.16 release, and has occurred with low frequency since at least 4.11. Users have not provided any descriptions, so additional information is currently unknown. ...
ApplicationReceivedScreenOrientationChangedNotificationDelegate does NOT work properly on Android
UE - Platform - Mobile - Aug 5, 2019ApplicationReceivedScreenOrientationChangedNotificationDelegate supports iOS but not Android. Probably, Java_com_epicgames_ue4_GameActivity_nativeOnConfigurationChanged should be useful for fix thi ...
Morph target is not applied on the first frame in Level Sequence
UE - Anim - Rigging - Dec 4, 2025When a skeletal mesh with morph targets spawns in the sequence, the morph is not reflected in the first frame. In the ProcessStage_SkinCache call of SkeletalMesh, MorphVertexBuffer->SectionIds is ...
ensure(false) being fired in FGenericParticlePairMidPhase::FindOrCreateConstraint from key collision
UE - Runtime - Simulation - Jan 27, 2025ensure(false) being fired in FGenericParticlePairMidPhase::FindOrCreateConstraint from key collision. The licensee reports one of their users reported this issue and they were able to reproduce a fe ...
[CrashReport] UE4Editor_Renderer!FGlobalShader::SetParameters<FRHIPixelShader * __ptr64,FRHICommandList>() [globalshader.h:134]
UE - Graphics Features - Jun 29, 2016This JIRA was created from crash reports submitted by users due to it being one of the top crashes occurring in 4.12.4 This might be a regression because the crash has only just started in 4.12.4. ...
Spot Light USD Export Produces Incorrect Intensity Values Based on Cone Angle and Source Radius
UE - Editor - Content Pipeline - USD - Apr 3, 2026UPDATE: Should be fixed as of CL#52537078 (fb7af1) USD: Bake all frames of exposure animation tracks. When exporting Unreal Engine spot lights from a level to USD, lights with identical EV intensit ...
Sequencer causes 3DWidget on BP vectors to snap to Actor when active
UE - Anim - Sequencer - Nov 15, 2025When we have Vectors in BP with Show 3D Widget enabled, the Transform Widget would always snap back to the Actor after we move the 3D Widget in-world. [Link Removed] Removing the _DaySequenceActor ...
Changing MaterialQualityLevel causes a crash due to a ShaderMap mismatch in UniformExpressionCache
UE - Rendering - Architecture - Materials - Nov 26, 2025A crash may occur when changing the MaterialQualitylevel via Scalability due to a race condition. The issue occurs because in ScalabilityCVarsSinkCallback(), when it creates the FGlobalComponentRec ...
GAS: Mixed replication mode and error in MinimalReplicationTags code
UE - Gameplay - Gameplay Ability System - Apr 6, 2022We're on 4.25.4. We recently turned on mixed mode replication for GAS, which seems to work fine and reduce bandwidth as expected. However one of our unit tests started failing with this error messag ...
When Constrain Aspect Ratio is enabled, the display position of DrawDebug rendering becomes misaligned
UE - Editor - Developer Usability - Jan 21, 2026Display DrawDebugSphere at the DefaultPawn's positionSet bConstrainAspectRatio=true on the DefaultPawn's CameraComponent Setting bConstrainAspectRatio=true in CameraComponent causes DrawDebug renderi ...