iced-rs/iced · error

Get user interface

Error message

Get user interface

What it means

Panic from `user_interfaces.get_mut(&id).expect("Get user interface")` at the start of RedrawRequested handling. The UI map must contain an entry for every open window; a missing entry is an internal invariant violation in the runtime's window/interface bookkeeping.

Source

Thrown at winit/src/lib.rs:783

                                .insert(id, ui.relayout(logical_size, &mut window.renderer));
                            layout_span.finish();

                            current_compositor.configure_surface(
                                &mut window.surface,
                                physical_size.width,
                                physical_size.height,
                            );

                            window.surface_version = window.state.surface_version();
                        }

                        let redraw_event =
                            core::Event::Window(window::Event::RedrawRequested(Instant::now()));

                        let cursor = window.state.cursor();

                        let mut interface =
                            user_interfaces.get_mut(&id).expect("Get user interface");

                        let interact_span = debug::interact(id);
                        let mut redraw_count = 0;

                        let state = loop {
                            let message_count = messages.len();
                            let (state, _) = interface.update(
                                &window.raw,
                                &window.waker,
                                slice::from_ref(&redraw_event),
                                cursor,
                                &mut window.renderer,
                                &mut messages,
                            );

                            if message_count == messages.len() && !state.has_layout_changed() {
                                break state;
                            }

View on GitHub (pinned to d146509d89)

Solutions

1. Update iced/winit to the latest release
2. Avoid racing Close actions against pending redraws
3. Replace expect with `if let Some(ui)` and skip the redraw if absent when forking

Example fix

// before
let mut interface = user_interfaces.get_mut(&id).expect("Get user interface");
// after
let Some(mut interface) = user_interfaces.get_mut(&id) else { continue; };

let Some(ui) = user_interfaces.get_mut(&id) else { continue; };

When it happens

Trigger: RedrawRequested fires for a window id whose user interface was removed earlier (closed window, failed relayout path at line 761, or interface removed by run_action without removing the window).

Common situations: Window closed via Action::Close while a redraw request was already queued; scale-factor/resize race that removed the UI but failed to reinsert it; forked runtime modifications.

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

• Remove user interface
• Caches must not be empty
• Downcast widget state
• Downcast on stateless state
• {error:?}

AI-assisted analysis of iced-rs/iced@d146509d89 (2026-09-11). Data as JSON: /api/errors/4380d435022e289c. Report an issue: GitHub.