FMultiReaderSingleWriterGT isn't thread safe

UE - Foundation - Core - May 17, 2016

From https://udn.unrealengine.com/questions/292741/fmultireadersinglewritergt-isnt-thread-safe.html: I've found that FMultiReaderSingleWriterGT has at least 2 bugs: The one that caused a deadlock ...

Reversed Animations don't play properly using Skeletal Mesh Pose and animations with Keep State in Sequencer

UE - Anim - Sequencer - Nov 26, 2018

The bug seems to only reproduce when setting animations in sequencer and only if the animations are set to "Keep state". Setting them to "restore default" makes the reversed animation play correctly ...

[CrashReport] UE4Editor_Engine!FAnimCurveBase::SetCurveTypeFlag() [animcurvetypes.cpp:18]

OLD - Anim - Jun 13, 2016

This Jira was created from CrashReports submitted by the public due to the high number of occurrences. Descriptions from users are provided below. Error message: Access violation - code c0000005 ( ...

Using a Macro to access a variable from another Actor causes a crash in Standalone

UE - Gameplay - Blueprint - Jun 8, 2015

Using a Macro to access a variable from another Actor causes a crash in Standalone. This does not seem to affect any other preview in editor, nor packaged games. Reproduced in 4.7.6, 4.8 Preview 4, ...

[5.4+] World Partition Landscape Spline Meshes Builder - Source landscape splines are not properly removed/hidden

UE - World Creation - Worldbuilding Tools - HLOD - May 30, 2025

LandscapeSplineActors and LandscapeSplineMeshesActors are not behaving as expected in 5.4 or 5.5. Testing in 5.4 the issue mostly seems to stem from issues with the Target Landscape -> Landscape Ac ...

[CrashReport] UE4Editor_Engine!FShaderCompilingManager::LaunchWorker() [shadercompiler.cpp:1573]

UE - Graphics Features - Aug 21, 2017

This is a common and longstanding crash that has occurred since at least 4.9. The issue appears to be due to missing ShaderCompileWorker.exe in binaries, but many of these crashes occur in the vani ...

When importing an FBX with Combine Meshes = False, one uasset will be created for the collection of assets.

Tools - Feb 4, 2016

When importing a mesh, there is an option to Combine Meshes, which by default is checked. Unchecking this option will bring in the individually named parts contained in the FBX as unique objects in ...

iOS fails during build step with OSS Facebook plugin enabled due to spaces in filepath

UE - Platform - Mobile - Feb 8, 2019

When a user tries to package or launch onto an iOS device they will fail at the build step due to:[3/8] sh Unzipping: /Users/Shared/Epic Games/UE_4.22/Engine/Source/ThirdParty/Facebook/IOS/FacebookS ...

Sequencer : Attaching a Possessable to multiple Spawnables across multiple cuts causes incorrect location restoration

UE - Anim - Sequencer - Nov 12, 2021

Regression No, according to affects versions 4.27 and 4.27.1 The restore process proceeds in the following order : 1. Remove spawnable actor in first cut (no effect because the actor is already r ...

Add support for motion data on SteamDeck (Steam Controller plugin)

UE - Gameplay - Input - Mar 7, 2025

We have a UDN user with a proposed change: https://udn.unrealengine.com/s/question/0D5QP00000yo70w0AA/add-support-for-gyro-motion-data-to-steam-controller-plugin?fromCase=1 Hi, we were adding gyr ...