slint-ui/slint · error

Cannot set callback {name}: {e}

Error message

Cannot set callback {name}: {e}

What it means

Error "Cannot set callback {name}: {e}" thrown in slint-ui/slint.

Source

Thrown at internal/live-preview/live_component.rs:152

    pub fn reload_properties_and_callbacks(&self) {
        // Set the properties
        for (name, value) in self.properties.borrow_mut().iter() {
            if let Some((global, prop)) = name.split_once('.') {
                self.instance()
                    .set_global_property(global, prop, value.clone())
                    .unwrap_or_else(|e| panic!("Cannot set property {name}: {e}"));
            } else {
                self.instance()
                    .set_property(name, value.clone())
                    .unwrap_or_else(|e| panic!("Cannot set property {name}: {e}"));
            }
        }
        for (name, callback) in self.callbacks.borrow_mut().iter() {
            let callback = callback.clone();
            if let Some((global, prop)) = name.split_once('.') {
                self.instance()
                    .set_global_callback(global, prop, move |args| callback(args))
                    .unwrap_or_else(|e| panic!("Cannot set callback {name}: {e}"));
            } else {
                self.instance()
                    .set_callback(name, move |args| callback(args))
                    .unwrap_or_else(|e| panic!("Cannot set callback {name}: {e}"));
            }
        }

        eprintln!(
            "Reloaded component {} from {}",
            self.component_name.as_deref().unwrap_or("<default>"),
            self.file_name.display()
        );
    }

    /// Set a hook that runs after each successful reload, receiving the new instance.
    pub fn set_post_reload_hook(&mut self, hook: impl Fn(&ComponentInstance) + 'static) {
        self.post_reload_hook = Some(Box::new(hook));
    }

View on GitHub (pinned to 3fd8f2ec03)

Solutions

1. Check the nested error and ensure the callback signature matches the declaration.
2. Verify the callback name exists on the component.

When it happens

Trigger: Thrown at internal/live-preview/live_component.rs:152 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of slint-ui/slint@3fd8f2ec03 (2026-08-19). Data as JSON: /api/errors/76388938368b6f40. Report an issue: GitHub.