Enabling ZenLoader causes editor crash when undoing Level Instance deletion

UE - Core - Systems - Sep 5, 2024

Crash reported through UDN. With ZenLoader enabled, deleting a level instance and triggering Undo causes a crash in  ULandscapeComponent::PostEditUndo() The user has provided an example project th ...

Instigator is no longer automatically set when spawning actors from blueprint

UE - Framework - Blueprint - Aug 20, 2024

Actors that are spawned from blueprints will no longer have their instigator automatically set to the instigator that spawned them. This is a regression in 5.5, because in 5.4 and earlier a null Ins ...

World Memory Leaks crash with a hidden sublevel to a redirector

Tools - Dec 8, 2020

From UDN: The reason it crashes is because Child doesn't get garbage collected, which is because it still has the RF_Standalone flag. UEditorEngine::EditorDestroyWorld clears RF_Standalone flag ...

Mutable: Child parameters hidden when intermediate Object Group uses "All Options"

UE - Runtime - Mutable - Mar 31, 2026

FCustomizableInstanceDetails::FillChildrenMap() unconditionally registers parent-child relationships via __ParentParamName metadata without verifying the parent exists in the active parameter list. ...

Adding a widget to a grid panel inside the grid panel tick can cause an out-of-bounds error

UE - Editor - UI Systems - Slate - Jan 25, 2021

This is caused by adding an item to a grid panel inside the grid panel iteration loop. The same operation to canvas panel goes well without any errors. The difference is that the array iteration in ...

Translucent Wireframe Materials Exhibit TSR Aliasing/Crawling Due To Incorrect Velocity Rendering When Set to Output Depth And Velocity

UE - Rendering - Features - Nov 27, 2025

Note that this bug potentially also affects a wide variety of material / geometry setups; however, a translucent wireframe setup is currently the main reproduction case. The issue may also be notice ...

[CrashReport] UE4Editor_SlateCore!IsResourceObjectValid() [drawelements.cpp:23]

Tools - Aug 2, 2018

No user comments in crash group 18 FSlateShaderResourceManager* FSlateDataPayload::ResourceManager; 19 20 static bool IsResourceObjectValid(UObject*& InObject) 21 ...

GameInstance and subsystem initialization order is incorrect for Play In Editor

UE - Gameplay - May 18, 2023

The order of world and game instance initialization is different between a true standalone game (cooked game or an editor build with -game) and a Play In Editor game. Specifically, in Play in Editor ...

editor crashes when variable inside of a struct is set to a class type then the object is moved to a new folder

UE - Gameplay - Blueprint - Mar 17, 2015

If a struct has a variable set to a class type, then the object of that class type is moved to a new folder in the editor, the struct will replace the class type with "class", which causes the edito ...

Pre-UE5 serialized FVariant FVector data corruption when deserialized in UE5

UE - Framework - LWC - Jan 15, 2024

FVariant is a struct that implements a union of data types, including FVector. When assigning an FVariant an FVector value in engine versions UE 4.27 or earlier, the FVariant will deserialize incorr ...