zed-industries/zed · error

Failed to attach safe-area probe: {error:?}

Error message

Failed to attach safe-area probe: {error:?}

What it means

The `?` on append_child for the safe-area probe divs failed: append_child returns a Result in web-sys, and this map_err wraps the JsValue error. The DOM refused to attach one of the probe elements (top/right/bottom/left) used to measure env(safe-area-inset-*). This is a generic DOM-mutation failure sentinel; the input at fault is the probe element/document pair being appended.

Source

Thrown at crates/gpui_web/src/viewport.rs:30

    pub(crate) visible_bounds: Bounds<Pixels>,
    pub(crate) insets: WindowInsets,
}

impl WebViewport {
    pub(crate) fn new(document: &web_sys::Document) -> anyhow::Result<Self> {
        let [top, right, bottom, left] =
            ["top", "right", "bottom", "left"].map(|edge| safe_area_probe(document, edge));
        let viewport = Self {
            safe_area_probes: [top?, right?, bottom?, left?],
            visible_bounds: Bounds::default(),
            insets: WindowInsets::default(),
        };
        let body = document
            .body()
            .ok_or_else(|| anyhow::anyhow!("Missing document body"))?;
        for probe in &viewport.safe_area_probes {
            body.append_child(probe)
                .map_err(|error| anyhow::anyhow!("Failed to attach safe-area probe: {error:?}"))?;
        }
        Ok(viewport)
    }

    pub(crate) fn observe_safe_area(&self, observer: &web_sys::ResizeObserver) {
        // Separate boxes detect redistribution between edges even when the
        // total inset, and therefore a single combined probe's size, is unchanged.
        for probe in &self.safe_area_probes {
            observer.observe(probe);
        }
    }

    pub(crate) fn update(
        &mut self,
        window: &web_sys::Window,
        canvas: &web_sys::HtmlCanvasElement,
    ) -> anyhow::Result<bool> {
        let canvas_bounds = canvas.get_bounding_client_rect();

View on GitHub (pinned to 9d272b0363)

Solutions

1. Retry initialization after the DOM is ready; appending before the document is fully parsed can transiently fail
2. Check for DOM-mutation blockers (strict CSP, frameworks clearing body) that reject programmatic child insertion
3. Log the {error:?} JsValue details to identify which edge probe failed and why

When it happens

Trigger: Thrown at crates/gpui_web/src/viewport.rs:30 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@9d272b0363 (2026-09-12). Data as JSON: /api/errors/9518db245a7bfd11. Report an issue: GitHub.