Exception generated launching Horde Agent built with 5.6

UE - Foundation - Horde - Server - Jul 28, 2025

The source of the problem seems to be using IOptionsSnapshot with a Singleton. Per the MS documentation for IOptionsSnapshot, "Is registered as Scoped and therefore can't be injected into a Singleto ...

Performance slowdown when ray tracing is disabled due to SetResidencyPriority

UE - Rendering - Architecture - RHI - Jul 17, 2025

When a game is compiled with ray tracing disabled (D3D12_RHI_RAYTRACING=0) and the GPU the game is running on becomes low on VRAM, frame time is negatively impacted and doesn't recover. The D3D12_RH ...

Niagara Regression - Looping particle with Spawn Burst Instantaneous on time 0.0 flickers for a frame between loops

UE - Niagara - Jul 16, 2025

Note: This worked correctly up to UE 5.4, but repros from UE 5.5 up to mainline latest. If a Niagara Emitter is set up with "Spawn Burst Instantaneous" on time 0.0, and the spawned particle(s) have ...

Inconsistent texture loading issue within material editor

UE - Rendering - Architecture - Materials - Jul 16, 2025

A licensee has reached out via EPS about a texture loading issue they are having in-editor. I summarized the most important points below:The issue relates to texture load failure associated with mat ...

Crash when clicking "Reset to Default" button on the Details Panel for the MaterialAttributeLayers material node.

UE - Rendering - Architecture - Materials - Jul 15, 2025

This crash repros from at least UE 5.3 and up to latest. The following assert is hit: Assertion failed: (Index >= 0) & (Index < ArrayNum) [Link Removed] [Line: 1067] Array index out of bounds: 0 in ...

CPU Lightmass generates different lighting results on a landscape if executed via a commandlet vs through the editor

UE - Graphics Features - Jul 3, 2025

Building lighting via commandlet and via editor are giving different results. To prevent one method from polluting the other via Swarm cache, the cache needs to be cleared in between tests. ...

TInstancedStruct used in native actor class loses reference to Instanced UObject after BP recompilation

UE - Framework - Blueprint Compiler - Jun 25, 2025

When a TInstancedStruct contains a UObject marked with EditInlineNew and DefaultToInstanced, the reference is lost after compiling the Blueprint but only when the struct is part of a native Actor cl ...

POST /v1/testdata API doesn't properly convert data to BSON

UE - Foundation - Horde - Server - Jun 24, 2025

Post: { "jobId": "685b12ad6765a5c9fefad260", "stepId": "a991", "key": "output-otem-job2", "data": { "Type": "Simple Report", "TestName": "EditorClientBoot", "Descript ...

GPU event descriptions are not properly formatted in Insight

UE - Rendering - Architecture - RHI - Jun 24, 2025

Context Unreal Insights displays Timing Insights that can include GPU timing information. Rendering code such as FDeferredShadingSceneRenderer::RenderPrePass() generate such events.Problem Certain f ...

Crash when using StaticDuplicateObject with mismathced Source and Destination class types

UE - Foundation - Jun 19, 2025

Starting in Unreal Engine 5.4, StaticDuplicateObject internally switched to using Unversioned Property Serialization (UPS) for performance reasons. However, UPS assumes the source and destination ob ...