facebook/react · error · Error

Not yet implemented.

Error message

Not yet implemented.

What it means

Fabric maintains a copy-on-write 'persisted' tree; when a text instance becomes hidden (Activity/Offscreen hidden mode), the renderer must clone it via cloneHiddenTextInstance - which Fabric deliberately has not implemented, so it always throws 'Not yet implemented.'. Hiding raw text subtrees is simply unsupported on this renderer.

Source

Thrown at packages/react-native-renderer/src/ReactFiberConfigFabric.js:558

  props: Props,
): Instance {
  const viewConfig = instance.canonical.viewConfig;
  const node = instance.node;
  const updatePayload = createAttributePayload(
    {style: {display: 'none'}},
    viewConfig.validAttributes,
  );
  return {
    node: cloneNodeWithNewProps(node, updatePayload),
    canonical: instance.canonical,
  };
}

export function cloneHiddenTextInstance(
  instance: Instance,
  text: string,
): TextInstance {
  throw new Error('Not yet implemented.');
}

export function createContainerChildSet(): ChildSet {
  if (passChildrenWhenCloningPersistedNodes) {
    return [];
  } else {
    return createChildNodeSet();
  }
}

export function appendChildToContainerChildSet(
  childSet: ChildSet,
  child: Instance | TextInstance,
): void {
  if (passChildrenWhenCloningPersistedNodes) {
    childSet.push(child.node);
  } else {
    appendChildNodeToSet(childSet, child.node);

View on GitHub (pinned to eafeac097b)

Solutions

1. Avoid Activity mode='hidden' / Offscreen around raw text on Fabric until RN ships support.
2. Render conditionally (return null when hidden) instead of hiding the text subtree.
3. Track the React Native issue for cloneHiddenTextInstance on Fabric and keep the feature behind a flag.

Example fix

// before
<Activity mode='hidden'>Loading...</Activity>

// after - avoid hiding a raw text subtree on Fabric
{isHidden ? null : 'Loading...'}

When it happens

Trigger: Rendering bare text (a string child) inside a subtree that Activity/Offscreen places into hidden mode (e.g. <Activity mode='hidden'>Loading...</Activity>) on the New Architecture/Fabric renderer with the persisted-node cloning path active.

Common situations: Experimenting with the experimental Activity/Offscreen APIs on React Native before Fabric implements hidden-text cloning; prerendering hidden content for instant reveal.

Related errors

• 320
• render: Unsupported Legacy Mode API.
• 559
• Not implemented.
• startGestureTransition is not yet supported in react-art.

AI-assisted analysis of facebook/react@eafeac097b (2026-08-21). Data as JSON: /api/errors/f5ca927811928456. Report an issue: GitHub.