Unreal Engine Issues
Unreal Engine Issues
World Memory Leaks crash with a hidden sublevel to a redirector
Tools - Dec 8, 2020From 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, 2026FCustomizableInstanceDetails::FillChildrenMap() unconditionally registers parent-child relationships via __ParentParamName metadata without verifying the parent exists in the active parameter list. ...
Translucent Wireframe Materials Exhibit TSR Aliasing/Crawling Due To Incorrect Velocity Rendering When Set to Output Depth And Velocity
UE - Rendering - Graphics Features - Nov 27, 2025Note 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 ...
GameInstance and subsystem initialization order is incorrect for Play In Editor
UE - Gameplay - May 18, 2023The 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 ...
Pre-UE5 serialized FVariant FVector data corruption when deserialized in UE5
UE - Framework - LWC - Jan 15, 2024FVariant 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 ...
Calling UBlueprintMapLibrary::GenericMap_Find with a non-existent key causes a memory leak
UE - Framework - Blueprint - Apr 15, 2025When Calling UBlueprintMapLibrary::GenericMap_Find with a non-existent key, the function construct the default structure in-place on the given pointer without destroying the object. This behavior ca ...
[AI] Debug Render Scene Proxy hits ensure for registering a delegate twice during level streaming.
UE - AI - Debugging - Aug 31, 2022Description from licensee: We're seeing an ensure get tripped up in FDebugRenderSceneProxy that says "DrawDelegate is already Registered!". Debugging the issue, we have confirmed that the DrawDeleg ...
[CrashReport] Assertion failed: !PinRef->bWasTrashed | UEdGraphPin::SerializePin()
UE - Gameplay - Blueprint - Aug 29, 2017This is a common and longstanding crash that has occurred since at least 4.15 and affected nearly 500 users. The CrashGroup was previously linked to [Link Removed], but that had specific repro step ...
Typo in "BaseEditorSettings.ini": under section [/Script/UnrealEd.ContentBrowserSettings], key "DisplayPluginFolder" (singular) should read "DisplayPluginFolders" (plural).
UE - Editor - Oct 11, 2025File "<ENGINE_PATH>/Engine/Config/BaseEditorSettings.ini" contains the following setting: [/Script/UnrealEd.ContentBrowserSettings] ; Whether to display the game project plugins in the Content Brow ...
WorldPartition RuntimeHashSet: non-deterministic URuntimePartitionPersistent UObject name causes unstable Cooked output (RuntimePartition:DebugColor)
UE - Engine Scaling - Streaming - HLOD - Jul 9, 2026During deterministic Cook / Package validation, the Cooked output of a WorldPartition map was found to vary non-deterministically between Cook runs. Diff detected in the DiffOnly Cook log:Serialize ...