title: WordPress using PHP7.3 in public_html, but MySQL extension error only showing in the dashboard
body: <p>I recently upgraded from PHP 7.1 to 7.3. The .htaccess files in <code>public_html</code>, <code>wp_content</code>, and <code>wp_includes</code> all show:</p>
  <pre><code>AddHandler application/x-httpd-ea-php73 .php .php5 .phtml
  &lt;IfModule mod_suphp.c&gt;
      suPHP_ConfigPath /opt/php71/lib
  &lt;/IfModule&gt;
  </code></pre>
  <p><code>wp_admin</code> is set to <code>AddHandler application/x-httpd-php71 .php</code>, since when I have it set to 7.3, I received the following error:</p>
  <blockquote>
  <p>Warning: Use of undefined constant WP_CONTENT_DIR - assumed 'WP_CONTENT_DIR' (this will throw an Error in a future version of PHP) in /home3/my-domain/public_html/wp-includes/load.php on line 141</p>
  <p>Your PHP installation appears to be missing the MySQL extension which is required by WordPress.</p>
  </blockquote>
  <p>Following advice I found on WordPress support, I added <code>define('WP_CONTENT_DIR', ABSPATH .'wp-content');</code> to wp-config. That removed the Undefined Constant error, but the MySQL error remains.</p>
  <p>Since MySQL is deprecated, I assume I don't need to download those extensions, but instead need to get WordPress to stop looking for them and use mysqli instead. But that shouldn't make a difference between 7.1 and 7.3, should it? And why does 7.3 work fine for the site, but not for the dashboard?</p>
  <p>And if the solution ends up being over my head (I don't want to screw around with things I don't know how to fix later), will there be any problems in using 7.3 in development and production, while the dashboard uses 7.1?</p>