Unable to launch project from Visual Studio using installed engine build

UE - Foundation - Build - Farm - Feb 23, 2017

When a code project's engine association is switched to a local binary version of a source engine, the project will fail to open from within Visual Studio. Error message says that UE4Editor-Project ...

Unable to create a 'World Soft Object Reference' Variable from the Variables Panel

UE - Framework - Blueprint Editor - Jun 21, 2018

Soft references to World objects (TSoftObjectPtr<UWorld>) cannot be directly created in blueprints. These types work fine in blueprints but cannot be directly created. The reason soft references are ...

Strange intermittent CCD behavior on constrained physics bodies

UE - Simulation - Physics - Oct 23, 2019

There is some strange issue with CCD where constrained CCD objects can get velocity nulled when hitting things while constrained, its very hard to reproduce normally in engine but happens often in V ...

Crash when quick binding a function in a class that extends LevelSequenceDirector

UE - Anim - Sequencer - Sep 16, 2020

The purpose was to create a Level Sequence Director inheritance class so that the same event could be reused in multiple sequencers. Attempting to quick-bind this base Level Sequence Director event ...

Python crash the engine at exit.

UE - Editor - Workflow Systems - Oct 25, 2022

A UDN reported various crashes at exit in the embedded Python library. I was able to repro the issue in Release-5.1 and trace it back at the point where python runs its garbage collection in Py_Fina ...

GAS and single process PIE: modifiable static variables accessed by server and client

UE - Gameplay - Gameplay Ability System - Nov 16, 2022

See: UAbilitySystemGlobals::HandlePreLoadMap GAS features static variables that are modified by both server and client, thus result in issues in single process PIE where they access the same memory ...

[MetaSounds] - Trigger inputs called by Execute Trigger Parameter refire on MetaSounds that become active after virtualization

UE - Audio - Aug 31, 2023

If trigger execute is called in Blueprint, it will fire every time the sound recovers from being virtual, even if it has not been called again. See video example: [Link Removed] Also occurs in Re ...

When duplicating the last point in a closed-loop spline, its metadata is inserted at the wrong index

UE - Editor - Workflow Systems - Nov 1, 2023

The SplineComponentVisualizer allows users to alt+drag on a spline point to duplicate it. When this is done on the last point of a spline marked as "closed-loop", the new point is correctly added at ...

check(bRenderStateCreated) fires in SendRenderDynamicData_Concurrent called from FRegisterComponentContext::Process

UE - Rendering - Architecture - RHI - May 18, 2026

FRegisterComponentContext::Process() in ActorComponent.cpp iterates over SendRenderDynamicDataPrimitives and calls SendRenderDynamicData_Concurrent() on each. The existing guard checks ::IsValid(Pri ...

Blueprint CDO contains removed component from parent class

UE - Gameplay - Blueprint - Apr 28, 2015

Blueprint CDO contains removed component from parent class. From the AnswerHub post: "It appears that if a component is removed from the C++ class, the CDOs for all of the blueprints remain unchang ...