Unreal Engine Issues
Unreal Engine Issues
Unable to launch project from Visual Studio using installed engine build
UE - Foundation - Build - Farm - Feb 23, 2017When 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 ...
Phaser module is malfunctioning
UE - Audio - Apr 9, 2019The phaser module that is part of the new Audio Engine causes audio from a Sound Cue to mute after playing for one second. The user states that the issue comes from the Phaser.cpp file producing a N ...
Python crash the engine at exit.
UE - Editor - Oct 25, 2022A 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 ...
Crash in AWorldDataLayers::InitializeDataLayerRuntimeStates() when quickly unloading then loading a sub-world partition
UE - Engine Scaling - Streaming - Data Layers - Mar 6, 2025From licensee: Since we integrated 5.5, we are experiencing a crash in AWorldDataLayers::InitializeDataLayerRuntimeStates() on this line check(ActiveDataLayerNames.IsEmpty() && LoadedDataLayerN ...
Custom Depth range is different than Pixel Depth range
UE - Rendering - Features - Sep 25, 2025Shaders that compare custom depth and pixel depth get wrong output values because the ranges are different. This error is most noticeable over large distances. The difference in ranges is due to t ...
When r.SSR.Stencil is enabled, there is wrong logic observed.
UE - Rendering - Features - Dec 19, 2025When r.SSR.Stencil is enabled, the areas with high roughnesss are not discarded and Unlit materials are incorrectly handled. See the linked EPS case (Additional Info URL) for a full explanation of ...
check(bRenderStateCreated) fires in SendRenderDynamicData_Concurrent called from FRegisterComponentContext::Process
UE - Rendering - RHI - May 18, 2026FRegisterComponentContext::Process() in ActorComponent.cpp iterates over SendRenderDynamicDataPrimitives and calls SendRenderDynamicData_Concurrent() on each. The existing guard checks ::IsValid(Pri ...
[CrashReport] UE4Editor_UMG!TBaseDelegate<FMargin>::operator=() [delegatesignatureimpl.inl:381]
UE - Editor - UI Systems - Aug 29, 2017This is a longstanding and common UMG crash that has affected more than 200 users since at least the 4.15 release. User DescriptionsI was working in the UI and undid several last changes in quick s ...
Simulated ability tasks not being cleaned up in UActorChannel::ReplicationMap
UE - Networking - Nov 20, 2018I've noticed the issue occurring in both 4.20.3 (CL 4369336) and 4.21.0 (CL 4541578). The user on AnswerHub has also noticed the issue in 4.20.2 (CL unknown) and claims the issue did not occur in 4. ...
Always Relevant actor may replicate incorrect movement mode when the walkable floor becomes irrelevant
UE - Runtime - Character - Feb 26, 2024When the character class is set to always relevant, if a client travels very far away from another character, such that the character is relevant but the component they're standing on is not (but al ...