Unreal Engine Issues
Unreal Engine Issues
Chaos : Rigid body sleeps when very small external force is applied by AddForce
UE - Runtime - Simulation - May 25, 2022When a small external force is applied to the rigid body, the VSmooth value is reset in the ResetVSmoothFromForces function. Since this function ignores the current velocity, a very small velocity ...
ApplyLocalExposure uses Output_ExtentInverse instead of Output_ViewportSizeInverse for bilateral grid UV
UE - Rendering - Features - May 18, 2026The ApplyLocalExposureCS shader in PostProcessLocalExposure.usf computes UV coordinates for the LumBilateralGrid 3D texture using Output_ExtentInverse (1/RenderTargetSize) instead of Output_Viewport ...
LineTraceSingleByChannel does not correctly use the collision response set for the channel being traced on
UE - Simulation - Physics - Nov 28, 2017There appears to be an issue with how raycasts are performed within PxScene. When performing the trace, only the collision response for the first ECollisionChannel seems to be considered. If all col ...
Widgets will bind input delegates to the Player Controller's Input Component, but never unbind them
UE - AI Workflows - UI Systems - UMG - Jan 30, 2024This is a bug introduced with 18468289 a while ago. We added this functionality for [Link Removed] Closed , which allows inp ...
Setting a struct bool property (bitfield) to itself writes the wrong value
UE - Framework - Blueprint Compiler - Sep 17, 2025There's an issue when assigning a bitfield bool to a native bool in Blueprints. Currently, the engine erroneously treats the memory for a local bool as a uint8 bitfield, which is undefined behavior. ...
[CrashReport] UE4Editor_Engine!FPointerToUberGraphFrame::~FPointerToUberGraphFrame()
UE - Gameplay - Blueprint - Aug 15, 2017This is a trending crash coming out of the 4.17.0 release. Users have not provided any descriptions of their actions when the crash occurred, however the callstack is very similar to [Link Removed] ...
[CrashReport] UE4Editor_Landscape!FLandscapeComponentSceneProxy::FLandscapeComponentSceneProxy() [landscaperender.cpp:680]
UE - LD & Modeling - Terrain - Landscape - Apr 11, 2018User comment in crash group:Wanted to delete a single field of my landscape wich is very big. Same error appears if I try to get a part of the landscape to another streaming level. Would be cool if ...
CheckCompilingPSOs assert in FMaterialPSORequestManager::MarkCompilationComplete fires occasionally
UE - Rendering - RHI - May 17, 2025Find the root cause and fix it. Potential issue based on logs:New RequestA is created in PrecachePSOs and its collection task is dispatched and finishedRequestA is waiting for compilation taskReque ...
LevelStreamingPersistence: BP variables that aren't Instance Editable get reset
UE - Engine Scaling - Streaming - Mar 6, 2026Context The LevelStreamingPersistence plugin can be used to remember and restore properties on actors and components that are part of a streamed level. Blueprint variables can be marked as instan ...
Undo/Redo can cause the gizmo to desync from a leaf-selected component
UE - Editor - Oct 18, 2021This is a regression from 4.27. This is happening because of the change to typed elements. UEditorEngine::PostUndo, when combined with the typed element changes causes the selection set to reorder ...