Valve Index Fails to Start with Monado: Screen Blinking and Red LED Issue

[lporterl]

When I start Monado with my Valve Index headset plugged in, the screen blinks 3-4 times, and the LED on the front of the headset switches to green briefly before turning red. After this, the headset does not attempt to reconnect or display anything further.

Hardware and Software:

OS: NixOS 25.05 (Warbler) x86_64
Kernel: Linux 6.12.9-xanmod1
Desktop Environment: Hyprland (Wayland)
CPU: Intel Core i9-13900KF
GPU: NVIDIA GeForce RTX 4080
VR Headset: Valve Index
Monado Version: (latest from NixOS unstable)

Steps to Reproduce:

1. Plug in the Valve Index headset (front LED on blue).
   

2. Start Monado service.
   

3. Observe the behavior: screen blinks 3-4 times, LED turns green, then red, and no further action occurs.
   

Logs or Outputs:
Below are the relevant logs from monado-service:

Jan 18 22:16:14 Main-PC monado-service[43804]: ################################################################################
Jan 18 22:16:14 Main-PC monado-service[43804]: #                                                                              #
Jan 18 22:16:14 Main-PC monado-service[43804]: #                        The Monado service has started.                       #
Jan 18 22:16:14 Main-PC monado-service[43804]: #                                                                              #
Jan 18 22:16:14 Main-PC monado-service[43804]: ################################################################################
Jan 18 22:16:14 Main-PC monado-service[43804]: U_PACING_LIVE_STATS=FALSE (nil)
...
Jan 18 22:16:32 Main-PC monado-service[43804]: ERROR [renderer_present_swapchain_image] vk_swapchain_present: VK_ERROR_UNKNOWN
Jan 18 22:16:33 Main-PC monado-service[43804]: WARN [vblank_event_func] vkWaitForFences: VK_TIMEOUT
Jan 18 22:16:34 Main-PC monado-service[43804]: WARN [vblank_event_func] vkWaitForFences: VK_TIMEOUT

Expected Behavior:
Monado should initialize the headset successfully, the LED should remain green, and the VR scene should be displayed correctly. I would like to test this with Beat Saber as an example application.

Additional Context:

My NixOS configuration includes the following setup for Monado:

{
  namespace,
  lib,
  config,
  pkgs,
  ...
}:
with lib;
let
  cfg = config.${namespace}.home.vr;
in
{
  options.${namespace}.home.vr = {
    enable = mkEnableOption "Enable FOSS VR stack";
  };

  config = mkIf cfg.enable {
    xdg.configFile = {
      "openxr/1/active_runtime.json".text = ''
        {
          "file_format_version": "1.0.0",
          "runtime": {
            "name": "Monado",
            "library_path": "${pkgs.monado}/lib/libopenxr_monado.so",
            "MND_libmonado_path": "${pkgs.monado}/lib/libmonado.so"
          }
        }
      '';
      "openvr/openvrpaths.vrpath".text = ''
        {
          "config" :
          [
            "${config.xdg.dataHome}/Steam/config"
          ],
          "external_drivers" : null,
          "jsonid" : "vrpathreg",
          "log" :
          [
            "${config.xdg.dataHome}/Steam/logs"
          ],
          "runtime" :
          [
            "${pkgs.opencomposite}/lib/opencomposite"
          ],
          "version" : 1
        }
      '';
    };
  };
}

I also have custom overlays for Monado defined in my Nix setup:

    { inputs, ... }:
    final: prev: {
      monado = prev.monado.overrideAttrs (old: {
        cmakeFlags = [
          (inputs.nixpkgs.lib.cmakeBool "XRT_FEATURE_SERVICE" true)
          (inputs.nixpkgs.lib.cmakeBool "XRT_OPENXR_INSTALL_ABSOLUTE_RUNTIME_PATH" true)
          (inputs.nixpkgs.lib.cmakeBool "XRT_HAVE_STEAM" true)
          (inputs.nixpkgs.lib.cmakeBool "CMAKE_EXPORT_COMPILE_COMMANDS" true)
          (inputs.nixpkgs.lib.cmakeBool "XRT_HAVE_SYSTEM_CJSON" true)
        ];
      });
    }

Please let me know if there’s any additional information or logs required.

[mateosss]

Hello, this is just my personal fork of monado you will have more luck asking in https://gitlab.freedesktop.org/monado/monado

I don't have a Valve Index near me anymore to test, but I remember there were some vulkan errors similar to yours when the render settings were too high for the GPU.

I would recommend you to set the following environment variables

export VIVE_LOG=debug # If you are using the "vive" driver
export XRT_COMPOSITOR_LOG=debug
export XRT_DEBUG_GUI=true # To see if the debug UI shows the valveindex menus or other info
export XRT_COMPOSITOR_DESIRED_MODE=0 # 0: 90hz, 2: 120hz, 1: 144hz, 4: 90hz lower res
export XRT_COMPOSITOR_SCALE_PERCENTAGE=100 # Usually 140 is preferred
export XRT_COMPOSITOR_COMPUTE=1 # enables atw

Maybe any of that helps. If not feel free to post the new output with those env vars again here, but you should probably reopen the issue in the main repo or ask on discord

Also there is this guide you might not know about: https://monado.freedesktop.org/valve-index-setup.html