Unreal Engine Issues
Unreal Engine Issues
Python crash the engine at exit.
UE - Editor - Workflow Systems - 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 - World Creation - Worldbuilding Tools - 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 - Graphics 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 - Graphics 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 ...
[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 - Gameplay - Player Movement - 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 ...
PakFiles: Unmounting PakFile while requests are still in progress causes assertion failure in UnMount
UE - Foundation - Mar 31, 2022[Link Removed] Licensee is using the chunk downloader. On Shutdown method of their GameInstance, they call FChunkDownloader->Finalize. When they quit the game (Alt+F4) during a chunck download an a ...
Build failure after nativizing any child Blueprint class with function override (regression).
UE - Gameplay - Blueprint - Jun 7, 2018Nativization regression in 4.20 preview 1. Cannot nativize overridden functions. Log Output:UATHelper: Packaging (Windows (64-bit)): D:/Projects/Unreal/NativizeMethod/Intermediate/Plugins/Nativized ...
Custom Primitive Data on BP instance not taking affect while in editor
UE - Rendering Architecture - Apr 5, 2023Original Repo is from 4.27, however, it still happens in 5.2. This is happening because the Instance Data system does not update the field UPrimitiveComponent::CustomPrimitiveDataInternal from the d ...