Crash when a subsystem calls GetSubsystemArray() on its owner while engine code is iterating on subsystems also obtained through GetSubsystemArray()

UE - Gameplay - Aug 6, 2024

In some occasions, engine code iterates over a certain subsystem type by calling FSubsystemCollection::GetSubsystemArray() and then calling some method on all subsystems of the returned array. This ...

Backwards-compatibility broken for the CDOs of Python-generated Unreal Types because of missing redirectors

UE - Editor - Workflow Systems - Feb 11, 2025

Previously, all Unreal Types generated by python scripts would be created inside package "/Engine/PythonTypes". This was changed by [CL 32478991 in ue5-main branch], which meant to "remove the restr ...

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 ...

"FVector contains NaN" on packaged builds for Debug configuration

UE - Graphics Features - Lumen - May 6, 2022

Customer Provided Description:This was experienced in UE 5.01 - custom installed engine (No changes to UE code, simply added the Debug build configuration, see the following command): "c:%ue_dire ...

Actors disappearing after saving a large number of modifications to world partition maps

UE - Editor - Workflow Systems - Nov 4, 2022

From Licensee: "We've encountered a world partition bug where newly created actors go missing in the viewport and Outliner after saving modifications to a large number of actors. This bug is partic ...

Ensure triggered inside Range Struct Customization when Property Node is no longer valid (e.g. when editing FFloatRange while FRuntimeFloatCurve editor is visible) [Ref. UE-341339]

UE - Editor - UI Systems - Nov 12, 2025

[Link Removed] was fixed by CL 46990575, successfully avoiding an ensure condition inside FIntervalStructCustomization::SetValue() when its Property Node is no longer valid. However, the same proble ...

Half precision is not supported for OpenGL ES 3.1 Pixel Shaders

UE - Platform - Mobile - Apr 6, 2018

Fix the cross compiler so half precision is supportedAdd a project setting to specify the default precision to support on ES31. Be sure the shader version takes this setting into account. — User des ...

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 ...

LayeredBlendPerBone without BlendRootMotionBasedOnRootBone exaggerates root motion

UE - Anim - Runtime - May 27, 2023

When BlendRootMotionBasedOnRootBone is false, the LayeredBlendPerBone is aggregating root motion of the child poses ontop of the base pose root motion.  (ie. if the first child pose's blend weight i ...

LIVE: EDITOR: SPEEDTREE: CRASH: When using SpeedTree with Fracture Tool editor crashes

UE - Graphics Features - Aug 11, 2014

Crash Reporter information added for 4.7.2 - 4.7.6 Also Reproduced in Main Promotable-CL-2527312 Crashes from current engine seem to be predominately from Open World Content Assets. including Rep ...