Unreal Engine Issues
Unreal Engine Issues
Unable to kill UnrealBuildTool, UBT no longer propegates sigterm
UE - Core - Cpp Tools - UnrealBuildTool - Aug 24, 2026When UBT is launched through one of the standard wrapper scripts, Ctrl-C no longer cancels the build. The `dotnet UnrealBuildTool.dll` process and its compile actions keep running to completion in t ...
VRS Cvar Crash during CollectPSOInitializers when CVarEnableVRS.GetValueOnRenderThread() causes Ensure failure
UE - Rendering - RHI - Aug 21, 2026We are running into an ensure that is triggered when CVarEnableVRS.GetValueOnRenderThread() is called on the game thread from FVariableRateShadingImageManager::IsAttachmentVRSEnabled. This happens ...
NavMoverComponent ConsumeNavMovementData returns true on any repeat call within the same game frame
UE - Runtime - Character - Aug 20, 2026UNavMoverComponent::ConsumeNavMovementData returns true on any repeat call within the same game frame, even when there is no nav movement to report. Callers that trust the return value then act ...
Enhanced Input Gesture keys (Pinch/Rotate/Flick) never release after touch ends — regression in 5.8
UE - Gameplay - Input - Aug 20, 2026POST LINK: https://forums.unrealengine.com/t/enhanced-input-gesture-keys-pinch-rotate-flick-never-release-after-touch-ends-regression-in-5-8/2745006 POST BODY:Summary An Input Action mapped directl ...
MRQ render with a slow output format drives Niagara GPU tick flush into its dummy-view path, causing an access violation in SetShaderParameters
UE - Rendering - Architecture - Niagara - Aug 18, 2026Sorry for the AI ticket, but it did a better job than I could: Rendering a level sequence through Movie Render Queue crashes the editor with an EXCEPTION_ACCESS_VIOLATION when the scene contains a N ...
Layered Blend Per Bone nodes evaluate to 0.0 weight with Blend Masks when s.AsyncLoadingThreadEnabled is active in Editor
UE - Runtime - Anim BP - Aug 11, 2026When starting the Editor, Layered Blend Per Bone nodes using Blend Masks inside dynamically linked Anim Layers completely ignore the blend pose (evaluating to 0.0 weight for all bones). Disconnectin ...
Mutable COIs built from ChildCustomizableObjects are engine only but do not denote that in anyway.
UE - Runtime - Mutable - Aug 10, 2026When creating a Mutable setup with nested Child COs, COIs can result with Editor-Only references, which will cause the COI not appear in the build manifest and the appearance to now spawn in game. ...
Notifies placed on the first frame of a montage using root motion don't fire
UE - Runtime - Animation - Aug 10, 2026This is a regression in 5.8 caused by 47265321. It's because we now perform the montage update and dispatch the queued notifies via CharacterMovementComponent::TickCharacterPose. But that all hap ...
Root motion extraction fails on blendspaces with bShouldMatchSyncPhases set
UE - Runtime - Animation - Aug 7, 2026There’s a bug with the bShouldMatchSyncPhases codepath in UBlendSpace::TickAssetPlayer. That codepath calls ResetBlendSamples to give a deterministic output when advancing time on the animations ow ...
Editor crashes when overriding Texture Collection in Material Instance
UE - Rendering - Architecture - Aug 6, 2026When a Material uses the DefaultTextureCollection and a Material Instance overrides it - or vice versa - the Editor will crash. Note: bindlessconfiguration=Minimal or higher must be enabled to use ...