Crash when placing a native UserWidget in a panel within another UserWidget

UE - Editor - UI Systems - Oct 7, 2019

The engine crashes when trying to initialize a native UserWidget within another widget. This happens because UUserWidget::GetSlotNames gets called before the widget tree is initialized, and we don't ...

Error: FAsyncPackage::LoadImports for <some asset>: Skipping import PaperTileMap /Script/Paper2D.Default__PaperTileMapActor:RenderComponent.PaperTileMap_0, depends on missing native class

UE - Gameplay - Blueprint Compiler - Jun 30, 2020

User reporting seeing this error start appearing in 4.25.1 (possibly 4.25.x, unsure if they were previously testing on 4.25.0 or not). It appears 'benign' as the expected data still gets loaded, bu ...

FTabManager::FindPotentiallyClosedTab Crash Due to Invalid Array Indexing

UE - Editor - Workflow Systems - May 25, 2023

As you can see from the above callstack it appears that calling RestoreArea can call FindPotentiallyClosedTab again higher in the stack, which can Remove() an entry from CollapsedDockAreas- this cau ...

Assertion occurs when undoing a Child State's unparenting from another Child State in AI State Trees, leading to a crash.

UE - AI - StateTree - Apr 15, 2022

Assertion occurs when undoing a Child State's unparenting from another Child State. Repro Rate: 5/5Assertion failed: false [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Public\Widgets\Views ...

Editor crash when Use Dynamic Material Instance is set to "True" on landscape

UE - LD & Modeling - Terrain - Landscape - Mar 23, 2018

Setting "Use Dynamic Material Instance" to true in the landscape details will cause the editor to crash. Reproduced in 4.19.0 CL 3944462 and 4.20 Main. This feature is not available in 4.18.3. ...

Doing a Rebuild in Visual Studio fails to compile

UE - Foundation - Cpp Tools - UnrealBuildTool - Apr 19, 2016

Attempting to use the Rebuild option in Visual Studio will fail to build the project. It instead produces a message that "Epic was unexpected". ...

OnComponentWake Event does not trigger when the physical body is awoken by a Force

UE - Simulation - Physics - Feb 27, 2025

OnComponentWake Event does not trigger when the physical body is awoken by a Force. The steps described on Steps To Reproduce is enough to replicate this behavior. The OnComponentWake event is only ...

Cannot continuously change Bone Name in SkeletalMesh Sampling Settings

UE - Anim - Jun 14, 2024

An access violation occurs in FNiagaraSkeletalMeshRegionBoneFilterDetails::HandleBoneNameComboBoxSelectionChanged() due to StringItem is nullptr. SkeletalMeshRegionCustomization.cpp void FNiagaraS ...

Crash on opening Control Rig asset that was created in UE5-EA

UE - Anim - Rigging - Control Rig - Nov 8, 2021

This issue was found from an external user on Twitter using UE5-Early Access - [Link Removed] The crash happens on asset load.  User says that they were following Gabriele's video - [Link Removed] ...

Game instance spawning object crashes .exe in packaged project

UE - Gameplay - Blueprint - Mar 19, 2015

If an actor is spawned using game instance blueprint, a packaged .exe will crash upon loading. Frequency: 2/2 Crash Reporter: [Link Removed] ...