The template root requires exactly one element. (vue/valid-template-root)

This error message is related to Vue.js templates and indicates that the root element of the template should contain only one element. In other words, the template should have a single parent element.

For example, the following code would produce the error message you mentioned:

<template>
  <div>
    <h1>Header</h1>
    <p>Paragraph 1</p>
    <p>Paragraph 2</p>
  </div>
  <div>
    <h2>Subtitle</h2>
    <p>Another paragraph</p>
  </div>
</template>

In this code snippet, there are two root elements (`<div>`), which is not allowed in Vue.js templates. To fix this error, you need to wrap all the elements inside a single parent element, like this:

<template>
  <div>
    <div>
      <h1>Header</h1>
      <p>Paragraph 1</p>
      <p>Paragraph 2</p>
    </div>
    <div>
      <h2>Subtitle</h2>
      <p>Another paragraph</p>
    </div>
  </div>
</template>

In this updated code, all the elements are wrapped inside a single parent `<div>`, which is the root element of the template. This should fix the error message.