StreamingGeneration: Actor desc mutator phase now writes ActorDescView directly, breaking the cluster-invariant check in ValidateContainerInstanceDescriptors

UE - Engine Scaling - Streaming - World Partition - May 22, 2026

This report is from an EPS case: We hit a regression upgrading our project from 5.7 to 5.8. Map Check (and any other path that ends up calling UWorldPartition::CheckForErrors) assert inside FWorld ...

[CrashReport] UE4Editor_MaterialEditor!SMaterialLayersFunctionsInstanceTree::UpdateThumbnailMaterial() [smateriallayersfunctionstree.cpp:1128]

Tools - Feb 27, 2018

No user comments in crash group 1114 for (TSharedPtr<FStackSortedData> Group : AssetChild->Children) 1115 { 1116 if (Group->ParameterInfo.Association == InAssociation) ...

Editor crash when saving a level instance in a folder with the same name as the level

UE - World Creation - Worldbuilding Tools - OFPA - Jan 27, 2023

Inconsistent ListView entry sizes can prevent the ListView from being scrolled to the bottom

UE - AI Workflows - UI Systems - Slate - May 4, 2022

Since the contents of a ListView are virtualized, the ListView estimates the size of the scroll box's contents based on the on-screen elements. This can lead to some situations where DistanceFromBot ...

Unexpected corrections when sliding against other characters

UE - Runtime - Character - Oct 19, 2023

We are seeing unexpected movement corrections sometimes when pushing one player character up against another character that isn't moving, or against other static primitives that have round features ...

Switch on custom enum causes compilation errors after Hot Reload

UE - Foundation - Core - Sep 28, 2015

If the project is hot reloaded while a Switch on Enum is inside of a blueprint which is switching on a custom enum, the switch will become corrupted. It changes the 'selection' pin to take a Byte pa ...

Camera behavior during "Orbit Pan Mode" (Alt+MMB+Drag) is wrong while piloting an actor

UE - Editor - Nov 18, 2025

In the Level Editor, dragging the mouse while the "Alt" key is pressed performs one of the "Orbit" movements: OrbitRotation, OrbitPan, OrbitZoom. The same can be done while Piloting an actor. Howev ...

[CrashReport] UE4Editor_Persona!FBoneDescription::SetScore() [bonemappinghelper.h:31]

OLD - Anim - Sep 14, 2017

This is a somewhat common crash that appears to occur only in 4.17.1 (possible regression?). Users have not provided any description of their actions when the crash occurs. Source Context 20 ...

NPC - Does not get updates from Material Parameter Collection changes in the editor

UE - Niagara - Sep 30, 2024

When an MPC is selected as the Source Material Collection for an NPC, all of its current parameters are carried over to the NPC with their current values. After that, if parameters are added to, rem ...

Double to float conversions of time in renderer causes precision issues

UE - Rendering - Architecture - Materials - Apr 8, 2026

In game sessions when the value for world time becomes large enough we start running into floating point precision issues. These issues can easily be seen in materials which do periodic animation b ...