Linux AppImage on Arch: WebKitWebProcess still SIGABRT in createAudioSink despite #2176 GST shim

[ClumZeez]

Summary

Current Linux AppImage still aborts WebKitWebProcess (SIGABRT / SI_TKILL) about 3 seconds after launch on Arch (Omarchy). The abort is RELEASE_ASSERT(audioSink) in MediaPlayerPrivateGStreamer::createAudioSink().

This is the failure block/buzz#2176 was meant to fix. The GST shim is present in this AppImage (usr/bin/buzz-desktop → buzz-desktop.bin) and still the renderer aborts.

Environment

• Buzz Linux AppImage, extracted to ~/.local/opt/buzz/squashfs-root (binaries dated 2026-08-22; desktop Exec=buzz-desktop)
• OS: Omarchy 4.0.0 (Arch Linux)
• Session: Hyprland / Wayland
• GPU: NVIDIA GeForce RTX 3060 Ti, driver 610.57.04
• Host GStreamer: 1.28.6 with gst-plugins-base / gst-plugins-good
• Bundled WebKitGTK 4.1 GNU build-id 2594e661ffa45aa2a47f83c2f2f10caaec9e273f (same build as Berd 0.6.2)

Not OOM (~8 GiB available). Launch: gtk-launch Buzz.desktop at 12:19:30 NZST; abort at 12:19:33 (PID 123026, 2026-08-25).

Abort site (from the core)

WTFCrashWithInfo in:

• file: Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp
• function: GstElement *WebCore::MediaPlayerPrivateGStreamer::createAudioSink()
• line: 1585

Offsets match exactly: libwebkit2gtk-4.1.so.0 + 0x7153cf (WTFCrashWithInfo) and + 0x335e100 (createAudioSink). Crashing thread held the audio-sink role "video".

The core also contains WebKit's GStreamer element %s not found. Please install it plus the autoaudiosink name.

usr/lib/gstreamer and usr/lib/gstreamer-1.0 still do not exist in the AppImage. AppRun.wrapped still injects:

GST_PLUGIN_SYSTEM_PATH=%s/usr/lib/gstreamer:%s
GST_PLUGIN_SYSTEM_PATH_1_0=%s/usr/lib/gstreamer-1.0:%s

Why this is not just "me-too" on #2176

#2176 installed a shim that unsets GST_PLUGIN_* values pointing into $APPDIR after AppRun.wrapped. That shim is on disk here and Buzz.desktop Exec=buzz-desktop, so the launch chain should be AppRun → AppRun.wrapped → shim → buzz-desktop.bin.

The web process still died at the same createAudioSink assert #2176 described (autoaudiosink / media-pipeline init → SIGABRT → blank window).

Possible remaining holes (I cannot tell which from this core alone):

1. The WebKit child does not inherit the cleaned env (or WebKit resets plugin paths).
2. Bundled Ubuntu WebKit still links a GStreamer whose compiled-in default plugin path is /usr/lib/x86_64-linux-gnu/gstreamer-1.0, which does not exist on Arch, so unsetting the linuxdeploy override is not enough.
3. createPlatformAudioSink() still returns NULL even when host plugins are visible (instantiation failure, not search-path).

Expected

Launching the AppImage on Arch should not abort the renderer when the UI creates a media player. Missing sink should fail the media element.

Suggested direction

Confirm whether WebKitWebProcess actually sees host autoaudiosink after the shim (GST_DEBUG=2 / gst-inspect-1.0 autoaudiosink under the AppImage env vs inside the web process). If the compiled-in default is still Debian multiarch, the shim needs to set GST_PLUGIN_SYSTEM_PATH_1_0 to the host plugin dir (/usr/lib/gstreamer-1.0 on Arch), not only unset the bundle path.

Berd 0.6.2 has the same WebKit build and no shim at all; same abort. Filing that on block/berd separately.

Not this bug

• block/buzz#2338 DMA-BUF / NVIDIA protocol error
• block/buzz#6339 Ubuntu .deb + system webkit 2.52.3
• block/buzz#2560 mixed host/bundle plugins on Ubuntu 26.04 (that AppImage had 274 plugins)

[ClumZeez]

Berd 0.6.2 hits the same abort with no GST shim at all: block/berd#195

[ClumZeez]

Follow-up (reproduced on desktop-v0.5.20)

Re-tested today on the same Omarchy/Arch + Hyprland + NVIDIA RTX 3060 Ti machine after installing Buzz_0.5.20_amd64.AppImage.

Stock launch still aborts the renderer. 0.5.20 still ships the #2176 unset-only GST shim (usr/bin/buzz-desktop → buzz-desktop.bin). About a second after start:

GStreamer element autoaudiosink not found. Please install it
(WebKitWebProcess): GLib-GObject-CRITICAL **: invalid (NULL) pointer instance

Then WebKitWebProcess SIGABRT / SI_TKILL. The UI process stays up with a blank window. coredump executable is the bundled webkit2gtk-4.1/WebKitWebProcess.

Correction to the original report

The original body said the host had gst-plugins-good. That was wrong on this machine: pacman.log has no gst-plugins-good install, and gst-inspect-1.0 autoaudiosink fails unless a user-local libgstautodetect.so is on GST_PLUGIN_PATH. Omarchy's default GStreamer set is gstreamer + gst-plugins-base (+ pipewire plugin). autoaudiosink lives in good.

That is enough to explain why the unset-only shim still dies here: after dropping the linuxdeploy override, host GStreamer has no autoaudiosink, and WebKit RELEASE_ASSERTs in MediaPlayerPrivateGStreamer::createAudioSink().

Hypothesis (2) from the original report (Ubuntu compiled-in plugin dir /usr/lib/x86_64-linux-gnu/gstreamer-1.0 missing on Arch) is still worth closing in the shim by setting host plugin dirs rather than only unsetting the bundle path. Arch's plugins are in /usr/lib/gstreamer-1.0.

Workaround that keeps the renderer alive on this host

GST_PLUGIN_PATH=$HOME/.local/lib/gstreamer-1.0  # libgstautodetect.so providing autoaudiosink
buzz-desktop --safe-rendering

--safe-rendering is a separate NVIDIA/Hyprland compositing escape hatch (WEBKIT_DMABUF_RENDERER_FORCE_SHM=1 + WEBKIT_DISABLE_COMPOSITING_MODE=1). Do not use WEBKIT_DISABLE_DMABUF_RENDERER=1 on current WebKitGTK (#3654). It is not the createAudioSink abort.

With autoaudiosink visible, the remaining GStreamer message is a warning only: missing MPEG-4 AAC decoder (audio/x-m4a) from a fuller gst-plugins-good / gst-libav set. That does not abort.

Suggested packaging fix (PR incoming)

In desktop/scripts/fix-appimage.sh shim, after dropping bundle-pointing GST_PLUGIN_* values, set GST_PLUGIN_SYSTEM_PATH_1_0 to existing host dirs (/usr/lib/gstreamer-1.0, /usr/lib64/gstreamer-1.0, /usr/lib/x86_64-linux-gnu/gstreamer-1.0), isolate GST_REGISTRY under the app cache so a failed launch cannot keep writing an empty ~/.cache/gstreamer-1.0/registry.x86_64.bin, and document gst-plugins-good / autoaudiosink on Arch in docs/linux-rendering-troubleshooting.md.

Leaving this issue open until that lands. Same abort on Berd 0.6.2 with no shim: block/berd#195

[ClumZeez]

PR: #6971

[BSTail]

Reproduced on v0.5.23 (AppImage) — newer than the 0.5.20 test above, and on a different GPU stack: LG Gram hybrid Intel iGPU + AMD dGPU (renderD128), Omarchy/Arch + Hyprland.

• Fresh install; deterministic abort ~1–2 s after launch. Three consecutive launches, all with byte-identical coredump stacks.
• Host GStreamer set matches the one described above: gstreamer + gst-plugins-base (+ pipewire/gtk plugins), no gst-plugins-good — gst-inspect-1.0 autoaudiosink fails. The AppImage bundles no gstreamer-1.0 plugins at all (verified by extracting the squashfs root).
• Core analysis (coredumpctl + gdb with debuginfod): abort() is called from inside the bundled libwebkit2gtk-4.1.so.0 during g_main_context_dispatch. Ruled out OOM (no kernel OOM kill, ample free RAM) and stack overflow (RSP ~21 KiB above the guard page). Consistent with the createAudioSink RELEASE_ASSERT diagnosis; I can't name the function — the bundled lib is stripped and Block's build isn't on debuginfod.
• One data point for the shim discussion: WebKitWebProcess's envp already contained WEBKIT_DMABUF_RENDERER_FORCE_SHM=1 without any manual --safe-rendering — that string lives in buzz-desktop.bin, so the app's own GPU heuristic set it (this machine is not NVIDIA). The abort still happened, which supports that this failure is independent of the dmabuf/compositing path.

So: 0.5.23 + no gst-plugins-good + hybrid Intel/AMD = same abort #6971 targets.

Filed by qwen3.8-27b-gsq-rco via opencode.