bevyengine/bevy · error

Could not create fetch_state, Please initialize all referenc

Error message

Could not create fetch_state, Please initialize all referenced components before transmuting.

What it means

Panic from QueryState::transmute_filtered: building the fetch state for the new query data failed because a component referenced by NewD has not been initialized/registered in the world yet. Transmutation reuses the old state's component ids, so any not-yet-initialized component in the new signature cannot be resolved.

Source

Thrown at crates/bevy_ecs/src/query/state.rs:701

        &self,
        world: impl Into<UnsafeWorldCell<'a>>,
    ) -> QueryState<NewD> {
        self.transmute_filtered::<NewD, ()>(world.into())
    }

    /// Creates a new [`QueryState`] with the same underlying [`FilteredAccess`], matched tables and archetypes
    /// as self but with a new type signature.
    ///
    /// Panics if `NewD` or `NewF` require accesses that this query does not have.
    pub fn transmute_filtered<'a, NewD: SingleEntityQueryData, NewF: QueryFilter>(
        &self,
        world: impl Into<UnsafeWorldCell<'a>>,
    ) -> QueryState<NewD, NewF> {
        let world = world.into();
        self.validate_world(world.id());

        let mut component_access = FilteredAccess::default();
        let mut fetch_state = NewD::get_state(world.components()).expect("Could not create fetch_state, Please initialize all referenced components before transmuting.");
        let filter_state = NewF::get_state(world.components()).expect("Could not create filter_state, Please initialize all referenced components before transmuting.");

        let mut self_access = self.component_access.clone();
        if D::IS_READ_ONLY {
            // The current state was transmuted from a mutable
            // `QueryData` to a read-only one.
            // Ignore any write access in the current state.
            self_access.access_mut().clear_writes();
        }

        NewD::update_component_access(&fetch_state, &mut component_access);
        NewD::provide_extra_access(
            &mut fetch_state,
            component_access.access_mut(),
            self_access.access(),
        );

        let mut filter_component_access = FilteredAccess::default();

View on GitHub (pinned to 396ca72708)

Solutions

1. Ensure all components referenced by the new query type are registered (spawn once, or world.init_component::<T>()) before transmuting
2. Transmute only between queries whose component sets are already initialized
3. Construct a fresh QueryState::new for the new signature instead

When it happens

Trigger: Thrown at crates/bevy_ecs/src/query/state.rs:701 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of bevyengine/bevy@396ca72708 (2026-08-20). Data as JSON: /api/errors/16435fc65ea870b9. Report an issue: GitHub.