Can’t perform a React state update on an unmounted component

Here is a React Hooks specific solution for


Warning: Can’t perform a React state update on an unmounted component.


You can declare let isMounted = true inside useEffect, which will be changed in the cleanup callback, as soon as the component is unmounted. Before state updates, you now check this variable conditionally:

useEffect(() => {
  let isMounted = true;               // note mutable flag
  someAsyncOperation().then(data => {
    if (isMounted) setState(data);    // add conditional check
  return () => { isMounted = false }; // cleanup toggles value, if unmounted
}, []);                               // adjust dependencies to your needs

Show code snippet

Extension: Custom useAsync Hook

We can encapsulate all the boilerplate into a custom Hook, that automatically aborts async functions in case the component unmounts or dependency values have changed before:

function useAsync(asyncFn, onSuccess) {
  useEffect(() => {
    let isActive = true;
    asyncFn().then(data => {
      if (isActive) onSuccess(data);
    return () => { isActive = false };
  }, [asyncFn, onSuccess]);

Show code snippet

More on effect cleanups: Overreacted: A Complete Guide to useEffect

Leave a Comment