DioxusLabs/dioxus · error

visible fragment creation requires an insertion site

Error message

visible fragment creation requires an insertion site

What it means

Internal diffing invariant: transitioning a fragment slot from empty to non-empty requires an insertion site to place the new content at, but none could be resolved. Indicates the mounted tree and vnode shape disagree.

Source

Thrown at packages/core/src/diff/node.rs:268

                    .dom
                    .clear_mounted_fragment_children(mount, slot.index());
            }
            (true, false) => {
                // Empty → non-empty: visible diffs stage new content at the
                // slot insertion site. Hidden/no-writer diffs only materialize
                // mount state, so there is no renderer placement to resolve.
                let context = state.context();
                let site = state
                    .has_writer()
                    .then(|| insertion_site_for_slot(mount, slot, state.dom, context));
                let children =
                    state
                        .dom
                        .begin_mounted_fragment_children(mount, slot.index(), new.len());
                state.create_children_at_site(
                    new,
                    parent,
                    |_| site.expect("visible fragment creation requires an insertion site"),
                    children,
                );
                state.dom.commit_mounted_fragment_children(children);
            }
            (false, true) => {
                state
                    .dom
                    .remove_nodes(state.to.as_deref_mut(), old, &old_mounts);
                state
                    .dom
                    .clear_mounted_fragment_children(mount, slot.index());
            }
            (false, false) => {
                let context = state.context();
                let fallback_site = state
                    .has_writer()
                    .then(|| insertion_site_for_slot(mount, slot, state.dom, context));
                let children =

View on GitHub (pinned to 24f6a829df)

Solutions

1. This is an internal invariant about fragment creation. Report it with a minimal reproduction to the Dioxus issue tracker.

When it happens

Trigger: Thrown at packages/core/src/diff/node.rs:268 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of DioxusLabs/dioxus@24f6a829df (2026-08-23). Data as JSON: /api/errors/008a18ac5f65fd8b. Report an issue: GitHub.