unable to acquire underlying compositor to create an xdg…

Error message

unable to acquire underlying compositor to create an xdg surface

What it means

Same weak-reference pattern as the positioner variant: get_xdg_surface upgrades a weak compositor reference to fetch the xdg_surface object for a WlSurface. If the strong compositor handle was already dropped, upgrade fails and the library panics. It means a Wayland xdg surface (the protocol object backing a toplevel) cannot be created because the compositor is unreachable.

Solutions

Keep the CompositorHandle alive until every surface creation completes; store it in your application state alongside the surfaces.
Create windows before any teardown of the compositor; avoid creating windows from tasks that can outlive the main handle.
Verify you are not using a Surface whose originating compositor has disconnected (e.g. after compositor crash/restart).
Restructure so surface creation happens synchronously in the same scope where the compositor handle exists.

Example fix

// before: surface outlives the compositor handle
let surface;
{
    let compositor = connect()?;
    surface = Surface::new(&compositor, handler, size);
} // handle dropped, later new/replace panics

// after: own the handle with the surface
struct Window {
    _compositor: CompositorHandle,
    surface: Surface,
}

Defensive patterns

Strategy: try-catch

Validate before calling

// Check compositor reachability before creating windows
if !compositor.can_upgrade() {
    eprintln!("compositor handle dead; cannot create window");
    return;
}

Type guard

fn can_create_surface(inner: &Weak<CompositorInner>) -> bool {
    inner.upgrade().is_some()
}

Try / catch

std::panic::catch_unwind(AssertUnwindSafe(|| Surface::new(&handle, handler, size)))
    .map_err(|_| WindowError::CompositorGone)

Prevention

Create windows in the same scope/lifetime as the compositor handle
Store the CompositorHandle in long-lived application state
Never spawn window-creation tasks that can outlive the main handle
Treat compositor disconnect as fatal for all pending window creations

When it happens

Trigger: Creating a new window/surface (via Surface::new or layer-shell paths) when the compositor handle backing the weak reference has been dropped, so the upgrade inside get_xdg_surface returns None.

Common situations: Window creation during or after Wayland compositor teardown; storing a Surface without keeping the CompositorHandle/WindowHandle alive; delayed window creation (e.g. spawning a window on a background task) after the initiating handle was dropped.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of linebender/druid@0f8b1195e4 (2026-09-10). Data as JSON: /api/errors/fad274097c08f7e5. Report an issue: GitHub.

Appendix: source

Thrown at druid-shell/src/backend/wayland/surfaces/mod.rs:165

    }

    fn shared_mem(&self) -> wlc::Main<WlShm> {
        match self.inner.upgrade() {
            None => panic!("unable to acquire underlying compositor to acquire shared memory"),
            Some(c) => c.shared_mem(),
        }
    }

    fn get_xdg_positioner(&self) -> wlc::Main<xdg_positioner::XdgPositioner> {
        match self.inner.upgrade() {
            None => panic!("unable to acquire underlying compositor to create an xdg positioner"),
            Some(c) => c.get_xdg_positioner(),
        }
    }

    fn get_xdg_surface(&self, s: &wlc::Main<WlSurface>) -> wlc::Main<xdg_surface::XdgSurface> {
        match self.inner.upgrade() {
            None => panic!("unable to acquire underlying compositor to create an xdg surface"),
            Some(c) => c.get_xdg_surface(s),
        }
    }

    fn zwlr_layershell_v1(&self) -> Option<wlc::Main<ZwlrLayerShellV1>> {
        match self.inner.upgrade() {
            None => {
                tracing::warn!(
                    "unable to acquire underyling compositor to acquire the layershell manager"
                );
                None
            }
            Some(c) => c.zwlr_layershell_v1(),
        }
    }
}

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