Unreal Engine Issues

Race condition in GetFunctionSig_Write() and other function signatures

A race condition exists in GetFunctionSig_Write() and other places where FNiagaraFunctionSignature  is lazily initialized because multiple worker threads can progress past if (!Sig.IsValid()) and st ...

MRQ render with a slow output format drives Niagara GPU tick flush into its dummy-view path, causing an access violation in SetShaderParameters

Sorry 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 ...

Values passed through VertexInterpolators are incorrect in the pixel shader on Niagara mesh particles when material uses SubUV animation

Passing through the vertex interpolator, the DebugFloat3Values output appears garbled, but if you remove the VertexInterpolator the particle’s position is accurately returned. This happens with Part ...

Niagara NDC GPU Instance Counter leak

In NiagaraDataChannelData.cpp, FNiagaraDataChannelDataProxy::EndFrame enqueues a GPU readback for each entry in PendingGPUReadbackBuffers, but the corresponding FNiagaraGPUInstanceCountManager::Free ...

Crash in FNiagaraEditorModule::PrecompileDuplicate() — null deref of Handle.GetEmitterData() in third "finish off the emitters" loop

Crash / null pointer dereference in FNiagaraEditorModule::PrecompileDuplicate(). File: Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Private/NiagaraCompiler.cpp Function: FNiagaraEditorModule::Pre ...

Niagara color picker user parameter preview no longer updates until confirmation

Starting with UE 5.4, the Color Picker Tool no longer updates preview values in real time for certain editor windows like Niagara when working with User Parameters. This behavior is a regression fr ...

Assets referenced solely in disabled Niagara Emitters are still cooked and packaged

Niagara Emitters, when disabled, appear to be removed from the Niagara System's packaged asset as evidenced by a sizeable reduction in size. However, if the Emitter referenced an asset, such as a st ...

Crash when undoing emitter deletion in Niagara System

ENiagaraCoordinateSpace is not exposed to Python, meaning the FXConverterUtilitiesLibrary create_script_input_enum function does not work when setting that parameter.

The user was having issues with setting the correct ENiagaraCoordinateSpace enum in their python script. This enum currently exists in the engine as both a user-defined enum (which is deprecated), a ...

Warning spam when binding the "Frame" property of the HeterogeneousVolumeComponent on the Sequencer

I think it doesn't like the "bPlaying == false" expression for the EditCondition meta tag on the UPROPERTY... You also get these warnings every single time the Sequencer plays through a keyframe on ...