facebook/react · error · Error

Unable to find node on an unmounted component.

Error message

Unable to find node on an unmounted component.

What it means

findHostInstance (the engine behind ReactDOM.findDOMNode) resolves a component instance to its DOM node via the internal fiber link on the instance. getInstance returned undefined while the object still has a render method, meaning it is a class instance whose fiber link is gone — a component that has already unmounted. findDOMNode is also deprecated, so this pattern should disappear entirely.

Source

Thrown at packages/react-reconciler/src/ReactFiberReconciler.js:164

  const fiber = getInstance(parentComponent);
  const parentContext = findCurrentUnmaskedContext(fiber);

  if (fiber.tag === ClassComponent) {
    const Component = fiber.type;
    if (isLegacyContextProvider(Component)) {
      return processChildContext(fiber, Component, parentContext);
    }
  }

  return parentContext;
}

function findHostInstance(component: Object): PublicInstance | null {
  const fiber = getInstance(component);
  if (fiber === undefined) {
    if (typeof component.render === 'function') {
      throw new Error('Unable to find node on an unmounted component.');
    } else {
      const keys = Object.keys(component).join(',');
      throw new Error(
        `Argument appears to not be a ReactComponent. Keys: ${keys}`,
      );
    }
  }
  const hostFiber = findCurrentHostFiber(fiber);
  if (hostFiber === null) {
    return null;
  }
  return getPublicInstance(hostFiber.stateNode);
}

function findHostInstanceWithWarning(
  component: Object,
  methodName: string,
): PublicInstance | null {

View on GitHub (pinned to eafeac097b)

Solutions

1. Replace findDOMNode with refs (createRef / callback refs) on the element you need — findDOMNode is deprecated and discouraged under StrictMode
2. Clear timers, subscriptions, and pending callbacks in componentWillUnmount so nothing runs after unmount
3. Null out stored refs when the component unmounts and check them before use
4. If a deferred callback must run, bail out early when the component (or its ref) is gone

Example fix

// before
componentDidMount() {
  this.timer = setTimeout(() => {
    const node = findDOMNode(this.child); // child may have unmounted -> throws
    node.focus();
  }, 1000);
}

// after
constructor(props) {
  super(props);
  this.nodeRef = React.createRef();
}
componentDidMount() {
  this.timer = setTimeout(() => {
    if (this.nodeRef.current) this.nodeRef.current.focus();
  }, 1000);
}
componentWillUnmount() {
  clearTimeout(this.timer);
}

// Pragmatic mounted-instance guard (fiber link exists = still mounted)
function isMountedClassInstance(x: unknown): boolean {
  return (
    x != null &&
    typeof x === 'object' &&
    typeof (x as any).render === 'function' &&
    (x as any)._reactInternals !== undefined
  );
}

When it happens

Trigger: ReactDOM.findDOMNode(instance) called after that component unmounted: timers (setTimeout/requestAnimationFrame) firing post-unmount, promise callbacks resolving late, event handlers or store subscribers holding stale child refs.

Common situations: Cleanup races in class components; findDOMNode(this.refs.child) after the child swapped out; instances captured in long-lived objects (stores, observers) and queried later.

Related errors

• Argument appears to not be a ReactComponent. Keys: ${keys}
• Unable to find node on an unmounted component.
• An unsupported type was passed to use(): ${String(usable)}
• Unknown Fiber. Needs to be a function component to inspect h
• Cannot ${action} through a Bridge that has been shut down.

AI-assisted analysis of facebook/react@eafeac097b (2026-08-21). Data as JSON: /api/errors/9b37812fbcd7198c. Report an issue: GitHub.