Unreal Engine Issues
Unreal Engine Issues
NaN Present on IOS after UE5.6 Because of Removal of MobileSpecularGGX
UE - Platform - Mobile - Systems - Sep 24, 2025In UE5.6 MobileSpecularGGX was removed and now mobile devices also run D_GGX. The problem is that there are still cases where very bright values are produced (image 1) and thus NaNs appear in the Bl ...
FKeyHandle internal static atomic counter can overflow on long running games depending on usage pattern
UE - Runtime - Animation - Sep 24, 2025Structure FKeyHandle stores an internal index, which is initialized from a static atomic counter in the default constructor: +----- FKeyHandle::FKeyHandle() { | static std::atomic<uint32> LastKey ...
Xcode 26/16.4 Metal Toolchain generates metallib's that are not compatible with iOS 16
UE - Platform - Mac - Sep 23, 2025Below is the error output from FirstPerson template as a C++ project: {+}../../../FirstPerson58CPP/Content/firstperson58cpp_sf_metal_es3_1_ios-metal_es3_1_ios.0.metallib, 5881486 bytes!2025-09-23 1 ...
Mutable constant texture variable with ClipUV mask only works with new experimental dynamic variable is connected as well
UE - Runtime - Mutable - Sep 22, 2025We are attempting to use Mutable in 5.6.1 and have encountered an issue which we are not sure how to resolve. The issue occurs when using the ClipWithUVMask node. In short we have a customizable o ...
Calling FOnlineIdentitySteam::GetLinkedAccountAuthToken without an internet connection won't execute callback delegate for WebAPI token type
UE - Online - Sep 22, 2025For the "WebAPI" TokenType, the call to execute the delegate is missing in the case where the SteamUserPtr is null or if BLoggedOn is false for the SteamUserPtr, so GetLinkedAccountAuthToken will ju ...
Seam visible when using a material with BumpOffset on a Nanite mesh
UE - Rendering - Features - Nanite - Sep 18, 2025When a material that uses BumpOffset is fed into the Emissive Color of Surface Opaque Default Lit material and then applied to a nanite mesh, a visible seam can be seen along edges and the intersect ...
Changing per layer parameters in a layered material that writes to RVT can cause temporary visual corruption
UE - Rendering - Architecture - Sep 12, 2025When using a layered material that writes to a runtime virtual texture. Sometimes when modifying a layer parameter in the material instance editor. The cached material data in the runtime virtual ...
[AI] Failed check in UMassSpawnerSubsystem::DestroyEntities due to EntityManager still procesing
UE - Engine Scaling - Mass - Sep 7, 2025It crashed when unspawning an AI which will destroy its entity. Inside DestroyEntities "IsProcessing" is true, but when it breaks into the debugger, "ProcessingScopeCount" is 0 (so IsProcessing shou ...
ensure(PinHelpers::UnresolvedPins.Num() == 0); fails after undoing in the editor
UE - Framework - Blueprint Editor - Sep 6, 2025The underlying cause is some edge case involving a math expression node, which does some perhaps naive things with a contained graph. ...
Crash when changing r.MaterialQualityLevel when FastGeo plugin enabled in cooked build
UE - Engine Scaling - Streaming - Sep 5, 2025The engine crashes when the r.MaterialQualityLevel is changed in a cooked game that uses the FastGeo Streaming Plugin. The crash doesn't repro with the same steps in Editor, just in a cooked build. ...