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 ...
Strange intermittent CCD behavior on constrained physics bodies
UE - Simulation - Physics - Oct 23, 2019There is some strange issue with CCD where constrained CCD objects can get velocity nulled when hitting things while constrained, its very hard to reproduce normally in engine but happens often in V ...
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 - Rendering Architecture - Shaders - 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 ...
Physics Substepping doesn't have the same effect from 4.15 to 4.16
OLD - Anim - Aug 8, 2017Physics Substepping doesn't have the same effect from 4.15 to 4.16. In 4.16+ the ponytail in the provided project will have a jitter effect even with substepping enabled. This is a regression: Work ...
[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 ...
[CrashReport] UE4Editor_UnrealEd!FBlueprintCompileReinstancer::ReplaceInstancesOfClass_Inner() [kismetreinstanceutilities.cpp:1880]
UE - Gameplay - Blueprint Compiler - Oct 5, 2017This is a somewhat common crash that has occurred throughout the 4.17 release. Users have not provided any description of their actions when the crash occurred. The callstack is similar to some ol ...
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 ...