Unreal Engine Issues
Unreal Engine Issues
High framerates result in desyncs with clients when using a dedicated server.
UE - Networking - Apr 17, 2019When a client operates at a high framerate on a dedicated server, their player movement will become desynced with the server. This manifests in different ways on different versions. In 4.21, it caus ...
Mutable: Child parameters hidden when intermediate Object Group uses "All Options"
UE - Anim - Mutable - Mar 31, 2026FCustomizableInstanceDetails::FillChildrenMap() unconditionally registers parent-child relationships via __ParentParamName metadata without verifying the parent exists in the active parameter list. ...
Launching on IOS, sessions do not appear in the Session Frontend
UE - Networking - Oct 17, 2018Licensee reports: Dug into this further and our iOS devices aren't receiving any of the handshake messages sent by the Session Frontend (or any other UDP messages for that matter) because multicast ...
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 ...
Linux: Assertion at splash screen when trying to open UE4Editor
UE - Platform - Linux - Mar 21, 2017I ran into this while looking to verify [Link Removed] at CL 3355923. I logged the issue I was verifying the fix for last night and have not updated anything locally, so the "OpenGL 4.3 not supporte ...
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 ...