Copying struct value using Set node from null source crashes

UE - Gameplay - Blueprint - Jun 23, 2015

Trying to access a Game Instance in a Blueprint's Construction Script results in a crash in 4.8 and 4.9. No crash occurred in 4.7.6 with the same Blueprint. This crash only seems to happen if the v ...

Event Dispatcher implementation called several times (number of bound refs increases every compile)

UE - Gameplay - Jun 26, 2018

The number of calls to the Event Dispatcher increase each time the blueprint actor containing the reference is compiled. This issue was not present in 4.18.3 (CL-3832480) but is in 4.19.2 (CL-403378 ...

OpenXR Remoting fails to attach actions to remoting session in 4.27

UE - Platform - XR - Jul 13, 2021

Regression from 4.26 where actions fail to bind when remoting in 4.27 Repro: using the Microsoft OpenXR Extensions plugin here:https://github.com/microsoft/Microsoft-OpenXR-Unreal/tree/main/MsftOpe ...

Parameter distributions can be reset to None in Cascade Particle Systems, causing Cascade to Niagara conversion to crash the editor.

UE - Niagara - Apr 18, 2022

Cascade to Niagara conversion causes the editor to crash due to any distribution parameter in the Particle Emitter being reset to none. Repro Rate: 4/4 Tested this in //UE4/Release-4.27 @ CL# 1831 ...

Virtualized Silent Sounds "Pop" When Played With New Mixer

UE - Audio - Sep 27, 2017

-Could not reproduce and only happens in the project linked below -Tested in 4.16 and Preview 4.18 and this can not be heard -Does not look like the .ini file is the cause of the issue -Other soun ...

[Soundfield Submix][Crash] - Unreal Ambisonics Crashes on Packaged Game and in Standalone

UE - Audio - Submixes - Jan 11, 2021

Issue was reported by a user on the Unreal Engine forms. I tried to package the game with the other encoding options and this appears specific to using the Unreal Ambisonics option.  I have only co ...

Assertion occurs when undoing a Child State's unparenting from another Child State in AI State Trees, leading to a crash.

UE - AI - StateTree - Apr 15, 2022

Assertion occurs when undoing a Child State's unparenting from another Child State. Repro Rate: 5/5Assertion failed: false [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Public\Widgets\Views ...

Crash on attempt to clear(NullifyInstance) of duplicated Hierachial Instanced Static Mesh

Tools - May 31, 2019

When creating an C++ Actor with a Hierarchical Instanced Static mesh. when duplicating such an actor with mesh instances, the instances are not visible on the level. In this state, calling HISM comp ...

Level Instance Property Override: Actor::Tags overridden pre-CS but clobbered by RerunConstructionScripts with no post-CS re-apply

UE - World Creation - Worldbuilding Tools - May 4, 2026

Summary When using the Level Instance Property Override system, overrides applied to `AActor::Tags` are silently lost for Blueprint actors whose Construction Script assigns or appends to `Tags`. The ...

Cooker Generated Packages: Actors can trigger the "load" of generated packages from linker load and load them incorrectly

UE - Foundation - Data Pipeline - Cooker - May 31, 2023

Generated packages have to be constructed by the cooker via FGeneratorPackage::CreateGeneratedUPackage. Some fields on the UPackage are set and ICookPackageSplitter->PopulateGeneratedPackage is call ...