emilk/egui · error

failed to get current context to resize surface

Error message

failed to get current context to resize surface

What it means

In `GlowIntegration::resize`, the code resizes the GL surface using `self.current_gl_context`, panicking with `expect` if that `Option` is `None`. `resize` requires a currently-usable OpenGL context; a `None` means the context is not current (it may live in `not_current_gl_context` after a suspend/make-not-current transition), so the surface cannot be resized now.

Source

Thrown at crates/eframe/src/native/glow_integration.rs:1435

            .expect("winit window doesn't exist")
    }

    fn resize(&mut self, viewport_id: ViewportId, physical_size: winit::dpi::PhysicalSize<u32>) {
        let width_px = NonZeroU32::new(physical_size.width).unwrap_or(NonZeroU32::MIN);
        let height_px = NonZeroU32::new(physical_size.height).unwrap_or(NonZeroU32::MIN);

        if let Some(viewport) = self.viewports.get(&viewport_id)
            && let Some(gl_surface) = &viewport.gl_surface
        {
            change_gl_context(
                &mut self.current_gl_context,
                &mut self.not_current_gl_context,
                gl_surface,
            );
            gl_surface.resize(
                self.current_gl_context
                    .as_ref()
                    .expect("failed to get current context to resize surface"),
                width_px,
                height_px,
            );
        }
    }

    fn get_proc_address(&self, addr: &core::ffi::CStr) -> *const core::ffi::c_void {
        self.gl_config.display().get_proc_address(addr)
    }

    pub(crate) fn remove_viewports_not_in(
        &mut self,
        viewport_output: &OrderedViewportIdMap<ViewportOutput>,
    ) {
        // GC old viewports
        self.viewports
            .retain(|id, _| viewport_output.contains_key(id));
        self.viewport_from_window

View on GitHub (pinned to 441971a776)

Solutions

1. Upgrade eframe/egui-glcontext — many context-suspend races around resize were fixed in later releases.
2. Ensure resize only happens while the context is current: re-check the order of make-current vs. resize calls in your fork/integration code.
3. Avoid triggering resize during teardown (guard against `Resized` events after you stop rendering).
4. If it happens on minimize, filter/ignore zero-sized or stale resize events as a workaround.

Example fix

// before
if let Some(new_size) = resize_request {
    integration.resize(viewport_id, new_size);
}
// after
if let Some(new_size) = resize_request {
    if integration.current_gl_context.is_some() {
        integration.resize(viewport_id, new_size);
    }
}

// Skip resize when the GL context is not current
if runner.current_gl_context.is_some() {
    runner.resize(viewport_id, new_physical_size);
} else {
    log::debug!("GL context not current; deferring resize");
}

fn can_resize(runner: &GlowIntegration) -> bool { runner.current_gl_context.is_some() }

When it happens

Trigger: A resize event (`ViewportCommand` handling or winit `Resized`) arrives while the glow GL context is in the not-current state — e.g. after `set_swap_interval`/suspend paths moved the context to `not_current_gl_context` and it was not made current again before the resize.

Common situations: Window minimize/restore or DPI-change storms on Windows/X11 where eframe temporarily drops the current context; calling resize during initialization or teardown; driver/driver-update environments where `make_current` failed earlier and left the context not current.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

• Harness::ui_id is only available for harnesses built with a
• viewport doesn't exist
• winit window doesn't exist
• Tried to update user texture.
• We should always find the root

AI-assisted analysis of emilk/egui@441971a776 (2026-09-12). Data as JSON: /api/errors/1fbb57a01ccf759a. Report an issue: GitHub.