errt_fix

Fixes ray tracing stutter in Elden Ring (PC, DirectX 12).

With ray tracing enabled, Elden Ring relinks its entire ray tracing pipeline on the render thread whenever a new material appears on screen. Each relink takes tens of milliseconds, which causes repeated frame-time spikes in dense areas such as forests. errt_fix prepares a pipeline that already contains every material, so these relinks no longer happen during gameplay.

Offline use only. errt_fix modifies the game process. Use it only with Easy Anti-Cheat disabled, in offline mode. Do not go online with it installed. See the legal notice.

Features

Feature	Setting	Description
RT pipeline cache	rt_cache	Records the game's RT material collections to disk and links a pipeline containing all of them in the background at startup. Requests from the game are answered with this prebuilt pipeline.
Material scan	rt_scan	Builds the complete cache in one session by finding every RT material shader in process memory.
BLAS refit thinning	refit_thinning	Animated foliage acceleration structures are updated every second frame instead of every frame.
Pipeline state reuse	pso_reuse	A pipeline the game requests more than once is created from the driver binary of the first compile.

Measured on an RX 9070 XT in a forest area: the worst frame dropped from 1035 ms to 61 ms, and BLAS refit thinning saves about 1 ms per frame.

Installation

1. Copy dinput8.dll and errt_fix.ini next to eldenring.exe (ELDEN RING\Game\).
2. Start the game with Easy Anti-Cheat disabled. Easy Anti-Cheat blocks unsigned DLLs, so errt_fix only works when the game runs without it, which also means offline mode.
3. Build the cache once: set rt_scan=1 in errt_fix.ini, start the game, wait about one minute in the main menu, quit, and set rt_scan=0 again.

The cache is stored in Game\errt_fix\rt_pipeline_cache.bin. It contains DXIL and pipeline descriptions only, so it works on both AMD and NVIDIA hardware. The first start after building it links the full pipeline in the background (about 30 seconds); later starts take under a second thanks to the driver's shader cache.

Materials that are not in the cache are added automatically when the game first uses them.

Log

Game\errt_fix\events.log lists cache activity, pipeline compiles longer than 20 ms, and a summary every five minutes. A line beginning with RT CACHE: new material recorded means a material was missing from the cache; it is included from the next start on.

Building

Requirements: Visual Studio 2022 (MSVC, Windows SDK) and CMake 3.20 or newer.

build.bat

The DLL and the default errt_fix.ini are written to dist\.

File	Purpose
src/main.cpp	dinput8.dll proxy, configuration, logging
src/hooks.cpp	D3D12/DXGI vtable hooks, BLAS refit thinning, overlay-safe Present hook
src/rt_cache.cpp	RT pipeline cache and material scan
src/pso_reuse.cpp	Pipeline state reuse
src/vtidx.c	Vtable slot indices taken from the Windows SDK headers

License

errt_fix is released under the MIT License. You may use, modify, fork and redistribute it, including in other projects, provided that the copyright notice and the license text are retained in all copies or substantial portions of the software. When publishing a fork or a derived mod, please also credit this project with a link to the original repository.

Legal notice

• No affiliation. errt_fix is an independent, unofficial project. It is not affiliated with, endorsed, sponsored or approved by FromSoftware, Inc., Bandai Namco Entertainment Inc., or any of their affiliates. ELDEN RING and all related names and marks are trademarks of their respective owners and are used here only to identify the game this software is compatible with.
• No game content. This repository contains only original source code. It does not include, and must not be used to distribute, any code, shaders, assets or other files belonging to the game. The cache file (rt_pipeline_cache.bin) is generated locally from the user's own installed copy of the game and must not be redistributed.
• Offline use only. errt_fix loads into the game process and changes how it uses the graphics API. It is intended solely for offline single-player use with Easy Anti-Cheat disabled. Using modified game files or processes in online play may violate the game's terms of service and can result in account restrictions or bans. Do not use errt_fix online.
• User responsibility. You are solely responsible for ensuring that your use of this software complies with the End User License Agreement and terms of service of the game and of any platform you use, and with the laws that apply to you.
• No warranty. The software is provided "as is", without warranty of any kind, as stated in the license. It may cause crashes, graphical errors or other malfunctions. Back up your save files before use. In no event shall the authors or contributors be liable for any claim, damages, account action, data loss or other liability arising from the use of this software.