[Solved]-Can't perform a React state update on an unmounted component when using custom hook for fetching data-Reactjs

you need to make sure the component is still mounted before trying to update the state:

    import { usestate, useeffect } from "react";
import axios from "axios";

const usefetch = (url) => {
      const [data, setdata] = usestate(null);
      const [error, seterror] = usestate(null);
      const ismounted=useref(null)
      useeffect(()=>{ ismounted.current=true; return()=>{ismounted.current=false}},[])
      useeffect(() => {
        axios
          .get(url)
          .then((response) => {
            if (ismounted.current)
            {setdata(response.data);}
          })
          .catch((err) => {
            if (ismounted.current)
            {seterror(err);}
          });
      }, [url]);
    
      return { data, error };
    };
    
    export default usefetch;

set a mutable value to true right after the component mounts, and set it to false when it is going to unmount.

before every setstate check if it is still mounted.