Race condition in full builds of UE4 engine source

UE - Foundation - Cpp Tools - UnrealBuildTool - Sep 26, 2019

This is a race condition caused by how "Clean.bat", a batch file used during rebuilds, tries to manually rebuild the UnrealBuildTool project when it runs. This causes a spam of UnrealBuildTool build ...

Linux crashes in the Project Browser without using the -nocef command

UE - Platform - Linux - Feb 22, 2022

When opening Unreal Editor on Linux, the Project Browser opens but is completely unresponsive. Shortly afterwards the editor will crash. If you use the -nocef command when opening the Editor, everyt ...

[CrashReport] Access Violation - UModelComponent::GetPhysicsTriMeshData() [modelcomponent.cpp:673]

UE - Simulation - Physics - Oct 2, 2017

This is a trending crash coming out of the 4.18 Previews. Users have not provided any descriptions of their actions when the crash occurred. The callstack is similar to [Link Removed], which was ju ...

[CrashReport] UE4Editor-Slate.dylib!FMenuStack::PostPush(TSharedPtr<IMenu, (ESPMode)0>, TSharedRef<FMenuBase,()

Tools - Dec 1, 2017

This is a longstanding but infrequent Mac crash that has occurred since at least 4.15. Users have not provided any descriptions. Callstack from Log[2017.11.19-04.18.41:283][ 0]LogSlate: Took 0.000 ...

WasRecentlyRendered() and GetLastRenderTimeOnScreen() still triggers when a skeletal mesh re-enters the view frustum despite being occluded.

UE - Rendering Architecture - Dec 4, 2024

AActor::WasRecentlyRendered() and UPrimitiveComponent::GetLastRenderTimeOnScreen() both still trigger when a skeletal mesh (occluded behind a wall) re-enters the player's view frustum after being ou ...

Converting BSP to static mesh on Linux causes the editor to crash

UE - Platform - Linux - Mar 11, 2016

Converting a BSP to a static mesh will freeze and crash the editor when done on Linux. Windows does not exhibit the same conversion crash. ...

Distant mesh / vista have visible Lumen bounces

UE - Rendering Architecture - Jun 15, 2024

Objects far outside of the Lumen Scene don't temporally accumulate screen traces, leading to heavy flickering. It appears that the temporal reprojection is failing when comparing the depth in "Scree ...

'Set Playback Position' node fires Timeline event even if 'Fire Events' is set to false

UE - Gameplay - Apr 30, 2015

'Set Playback Position' node fires Timeline event even if 'Fire Events' is set to false. User Description: Basically using the set playback position node to set a new time position for a timeline ...

Asset localization does not work properly for Paper2D related assets such as Flipbook

UE - Foundation - Mar 18, 2022

This issue is resolved by changing Paper2D's LoadingPhase to PostConfigInit, but this is a workaround. We suggest a better long term fix via AssetRegistry changes (see comments). In the default la ...

ACineCameraAttachMount's "Target Actor" constraint does not work with Spawnables or Replaceables in Sequencer

UE - Virtual Production - Tools - Virtual Camera - Aug 12, 2025

Constraints (UTickableConstraint) are usually created throuh the "Animation" tab available in the Editor's "Animation Mode". When created through that interface while Sequencer is open, the internal ...