title: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema
body: <p>I have been stock on this error on my project when I add <code>&quot;proxy&quot;: &quot;http://localhost:6000&quot;</code>
  in my package.json.</p>
  <p>This is the error response after yarn start.</p>
  <blockquote>
  <p>Invalid options object. Dev Server has been initialized using an
  options object that does not match the API schema.</p>
  <ul>
  <li>options.allowedHosts[0] should be a non-empty string. error Command failed with exit code 1. info Visit
  <a href="https://yarnpkg.com/en/docs/cli/run" rel="noreferrer">https://yarnpkg.com/en/docs/cli/run</a> for documentation about this
  command.</li>
  </ul>
  </blockquote>
  <p>But everything is fine when I remove the <code>&quot;proxy&quot;: &quot;http://localhost:6000&quot;</code>.</p>
  <p>This is on my package.json:</p>
  <pre><code>{
    &quot;name&quot;: &quot;client&quot;,
    &quot;version&quot;: &quot;0.1.0&quot;,
    &quot;private&quot;: true, 
    &quot;dependencies&quot;: {
      &quot;@material-ui/core&quot;: &quot;^4.12.3&quot;,
      &quot;@testing-library/jest-dom&quot;: &quot;^5.16.1&quot;,
      &quot;@testing-library/react&quot;: &quot;^12.1.2&quot;,
      &quot;@testing-library/user-event&quot;: &quot;^13.5.0&quot;,
      &quot;axios&quot;: &quot;^0.24.0&quot;,
      &quot;moment&quot;: &quot;^2.29.1&quot;,
      &quot;react&quot;: &quot;^17.0.2&quot;,
      &quot;react-dom&quot;: &quot;^17.0.2&quot;,
      &quot;react-file-base64&quot;: &quot;^1.0.3&quot;,
      &quot;react-redux&quot;: &quot;^7.2.6&quot;,
      &quot;react-scripts&quot;: &quot;5.0.0&quot;,
      &quot;redux&quot;: &quot;^4.1.2&quot;,
      &quot;redux-thunk&quot;: &quot;^2.4.1&quot;,
      &quot;web-vitals&quot;: &quot;^2.1.2&quot;
    },
    &quot;scripts&quot;: {
      &quot;start&quot;: &quot;react-scripts start&quot;,
      &quot;build&quot;: &quot;react-scripts build&quot;,
      &quot;test&quot;: &quot;react-scripts test&quot;,
      &quot;eject&quot;: &quot;react-scripts eject&quot;
    },
    &quot;eslintConfig&quot;: {
      &quot;extends&quot;: [
        &quot;react-app&quot;,
        &quot;react-app/jest&quot;
      ]
    },
    &quot;browserslist&quot;: {
      &quot;production&quot;: [
        &quot;&gt;0.2%&quot;,
        &quot;not dead&quot;,
        &quot;not op_mini all&quot;
      ],
      &quot;development&quot;: [
        &quot;last 1 chrome version&quot;,
        &quot;last 1 firefox version&quot;,
        &quot;last 1 safari version&quot;
      ]
    },
    &quot;proxy&quot;: &quot;http://localhost:6000&quot;
  }
  </code></pre>