title: WordPress 5.5.3. Fatal error: Cannot redeclare _wp_register_meta_args_whitelist() (previously declared in …\wp-includes\meta.php:1409) in …\wp-include
body: <p>I recently started to get the same exact error regularly. First I got the error (<code>Fatal error: Cannot redeclare _wp_register_meta_args_whitelist() (previously declared in …\wp-includes\meta.php:1409) in …\wp-includes\deprecated.php on line 4064</code>), I manually update to <strong>WordPress 5.5.3</strong>. And it resolved the problem. Then I updated to plugins when I able to reach admin panel.</p>
  <p>Next day, I faced up with the same error. Again I deleted <code>wp-includes</code> and <code>wp-admin</code>. Paste freshly downloaded <code>wp-includes</code> and <code>wp-admin</code>. Overwrite existing files on <code>wp-content</code>. Then the error disappeared again. I went to admin panel to update the plugins.</p>
  <p>Today I woke up and see that I have same error. I just deleted <code>wp-includes</code> and <code>wp-admin</code> and uploaded them, and problem is gone again but I’m worried about to get same error tomorrow. Is anyone having the same problem?</p>
  <p>Hosting <em>WordPress 5.5.3 Turkish</em> version in <em>Windows Server</em>. Running <em>PHP version: 7.2.26</em>.
  Active plugins:</p>
  <ul>
  <li><a href="https://wordpress.org/plugins/custom-css-js/" rel="nofollow noreferrer">Simple Custom CSS and JS 3.34</a></li>
  <li><a href="https://wordpress.org/plugins/elementor/" rel="nofollow noreferrer">Elementor 3.0.13</a></li>
  <li><a href="https://wordpress.org/plugins/one-click-demo-import/" rel="nofollow noreferrer">One Click Demo Import 2.6.1</a></li>
  <li><a href="https://wordpress.org/plugins/redirection/" rel="nofollow noreferrer">Redirection 4.9.2</a></li>
  <li><a href="https://wordpress.org/plugins/topbar-call-to-action/" rel="nofollow noreferrer">TopBar Call To Action 1.0.9</a></li>
  <li><a href="https://wordpress.org/plugins/wordpress-seo/" rel="nofollow noreferrer">Yoast SEO 15.2.1</a></li>
  <li><a href="https://wordpress.org/plugins/display-php-version/" rel="nofollow noreferrer">Display PHP Version 1.5</a></li>
  <li><a href="https://wordpress.org/plugins/akismet/" rel="nofollow noreferrer">Akismet Anti-Spam 4.1.7</a></li>
  </ul>
  <p>And the lines on the error(the version that before I delete the wp-includes and upload new version):</p>
  <p><strong>…\wp-includes\meta.php</strong>:<em>1409</em></p>
  <pre><code>function _wp_register_meta_args_whitelist( $args, $default_args ) {
      return array_intersect_key( $args, $default_args );
  }
  </code></pre>
  <p><strong>…\wp-includes\deprecated.php</strong>:<em>4064</em></p>
  <pre><code>function _wp_register_meta_args_whitelist( $args, $default_args ) {
      _deprecated_function( __FUNCTION__, '5.5.0', '_wp_register_meta_args_allowed_list()' );
  
      return _wp_register_meta_args_allowed_list( $args, $default_args );
  }
  </code></pre>