Describe the bug

SteamVR 2.16.7 build 23791826 breaks ALVR's direct-mode path on Linux. vrcompositor starts and completes init in ~0.2 s, but vrserver times out after 10 s claiming the compositor is not running. vrmonitor then reports Unable to get compositor interface (303) and shows the "A key component of SteamVR isn't working correctly. Please reinstall SteamVR" dialog (its "More info" link is dead).

Streaming still starts, but ALVR logs Desync detected. Attempting recovery. continuously. That warning fires when game render latency exceeds 250 ms, rate-limited to once per 100 ms — and it fires at the maximum allowed rate, so the condition is continuous rather than intermittent. In the headset it presents as heavy lag with the client re-warping a stale frame: turning your head exposes the unrendered border of the previous frame, so the world looks flat.

Rolling SteamVR back to the previous Steam branch (build 22542555) fixes it completely. Clean bisect on one variable — no other configuration changed between the two runs.

Relevant log excerpts.

vrcompositor.txt — compositor comes up fine:

[Info] - Direct mode: enabled
[Info] - Headset is using direct mode
[Info] - Startup Complete (0.240239 seconds)

vrserver.txt — ~10 s later, vrserver disagrees:

[Info] - timeout - vrcompositor process is not running.
[Info] - Processing message VRMsg_StartVRCompositor from vrmonitor took 10.5 seconds
[Info] - Processing message VRMsg_StartVRCompositor from vrserver took 10.4 seconds

vrmonitor.txt:

[Info] - Unable to get compositor interface (303)
[Info] - [Status Alert] Something is wrong (303)
[Info] - Drops over entire run:- ... - Total 0 in 0 frames

ALVR streamer log, starting ~2 s after the encoder comes up:

[INFO] CEncoder client connected, pid <vrcompositor>
[INFO] Using VAAPI encoder
[WARNING] Desync detected. Attempting recovery.     <- hundreds, every 100 ms

Already ruled out:

• Network — reproduces identically over USB 3.2 wired.
• GPU performance — GPU utilisation stayed at 0–20 % for entire sessions, zero amdgpu/DRM errors in the kernel log. 250 ms of render latency on an idle GPU is a stall, not saturation. Render resolution and SteamVR supersampling changes had no effect.
• Refresh-rate mismatch — SteamVR initially requested 90 Hz while ALVR's virtual display offered only 72 Hz. Setting ALVR to 90 Hz made all three agree (@90.000008Hz) and changed nothing.
• The vrlink driver — disabled via "driver_vrlink": {"enable": false}, confirmed not loaded (no VRLINKQ_* devices). Desyncs unchanged. This is not the VPN scenario from #910 — no VPN interface was up during any of these runs, and disabling vrlink did not help.
• Reinstalling SteamVR — the 303 is not an install-integrity problem.

Possibly relevant (hypothesis, not proven): ALVR's driver advertises older direct-mode interfaces than the drivers shipped with 2.16.7:

alvr_server: IVRDisplayComponent_002  IVRDriverDirectModeComponent_007
lighthouse : IVRDisplayComponent_003  IVRDriverDirectModeComponent_009
vrlink     : IVRDisplayComponent_003  IVRDriverDirectModeComponent_009

If something in 23791826's compositor/vrserver registration path began assuming _003/_009, that would explain a driver that still loads and produces an HMD and a video stream, while the compositor never completes its handshake with vrserver. I have not verified this — the bisect is solid, the explanation is speculation.

To Reproduce

1. Install ALVR v20.14.1 (Linux streamer) and SteamVR 2.16.7 build 23791826.
2. Launch SteamVR from the ALVR dashboard and connect a Quest 2, over either USB 3.2 or Wi-Fi.
3. Observe timeout - vrcompositor process is not running in vrserver.txt and Unable to get compositor interface (303) in vrmonitor.txt, roughly 10 s after vrcompositor.txt logs Startup Complete.
4. Observe continuous Desync detected. Attempting recovery. in the ALVR streamer log, and severe lag / stale-frame reprojection in the headset.
5. Switch SteamVR to the previous Steam branch (build 22542555) and repeat step 2. All symptoms disappear.

Expected behavior

vrserver should register vrcompositor after it reports Startup Complete, no 303 should be raised, and frame pacing should proceed normally — as it does on build 22542555 with an otherwise identical configuration.

System Information

• Steam client version (build number or date): 1784778118
• SteamVR version: 2.16.7, build 23791826 (broken) — verified working on build 22542555 via the previous branch
• Distribution (e.g. Ubuntu): openSUSE Tumbleweed, kernel 7.1.4-1-default, KDE Plasma on Wayland
• GPU / driver: AMD Radeon RX 9070 (RADV, gfx1201), Mesa 26.1.5 (radeonsi, ACO, DRM 3.64)
• Headset: Meta Quest 2 via ALVR v20.14.1

paste.txt steam-runtime-system-info

steam-minidumps.tar.gz

steam-logs.tar.gz

Additional context

A note on the template's request to test the latest beta: build 23791826 was the current build when this was found. I am running the previous branch now because it is the only configuration in which the headset is usable. Happy to switch back to beta and gather anything specific you need — just say what to capture.

Two existing issues look related but are not the same thing:

• #910 — same build, but attributes the failure to vrlink binding VPN interfaces. My case has vrlink disabled and no VPN present, and still fails, so that cannot be the whole cause.
• alvr-org/ALVR#3297 — tracks the Desync detected warning from the ALVR side.