zed-industries/zed · error

attempted to read a window that is already on the stack

Error message

attempted to read a window that is already on the stack

What it means

A reentrancy guard in App::read_window: window access uses a stack to detect recursive access, and reading a window whose handle is already on the stack panics with 'attempted to read a window that is already on the stack'. It fires when code running inside a window's context (layout, paint, or an update) synchronously re-enters the same window via read_window — reentrant access that GPUI forbids because it would alias mutable window state.

Source

Thrown at crates/gpui/src/app.rs:2885

    where
        T: 'static,
    {
        GpuiBorrow::new(handle.clone(), self)
    }

    fn read_entity<T, R>(&self, handle: &Entity<T>, read: impl FnOnce(&T, &App) -> R) -> R
    where
        T: 'static,
    {
        let entity = self.entities.read(handle);
        read(entity, self)
    }

    fn update_window<T, F>(&mut self, handle: AnyWindowHandle, update: F) -> Result<T>
    where
        F: FnOnce(AnyView, &mut Window, &mut App) -> T,
    {
        self.update_window_id(handle.id, update)
    }

    fn with_window<R>(
        &mut self,
        entity_id: EntityId,
        f: impl FnOnce(&mut Window, &mut App) -> R,
    ) -> Option<R> {
        App::with_window(self, entity_id, f)
    }

    fn read_window<T, R>(
        &self,
        window: &WindowHandle<T>,
        read: impl FnOnce(Entity<T>, &App) -> R,
    ) -> Result<R>
    where
        T: 'static,
    {

View on GitHub (pinned to 9d272b0363)

Solutions

1. Check whether the window is already on the stack (or pass the live &mut Window down) instead of re-entering via the handle
2. Defer the read with cx.defer/spawn so it runs after the current window access completes
3. Restructure callers to take Window as a parameter through the call chain rather than re-fetching it

When it happens

Trigger: Thrown at crates/gpui/src/app.rs:2850 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@9d272b0363 (2026-08-20). Data as JSON: /api/errors/2e9f04c321218725. Report an issue: GitHub.