I have a Nuxt3 project. Its work find on hello, but there is an error message Page not found: /api/hello on /api/hello

pages/hello.vue

<template>
  <div>
    <h1>{{ message }}</h1>
  </div>
</template>
<script setup>
const { data: message } = useFetch('/api/hello');
</script>

Can anyone have idea on this unusual behavior? Thanks in advance.