I have an API which gets records from Mongodb. When I call records from db, records are coming, there is no problem. But it's not working on the host. There is an error on console like Failed to load resource: the server responded with a status of 404 () api/improve-language?cat=general:1.

My codes where I'm trying to get datas:

useEffect(() => {
    getAllData(category)
  }, [])

  async function getAllData(cat){

    if(cat){
      cat = `?cat=${cat}`
    } else{
      cat = ``
    }
    
    axios
    .get(`/api/improve-language${cat}`)
    .then(res => {
      setAllWords(res.data)
      setNeverAskedWords(res.data)
      newQuestionAndAnswers(res.data)
    })
    .catch(err =>{
      console.log(err)
    })

  }