title: Wordpress Fatal error after migrating from php5.6 to php7
body: <p>My WP site is currently on php 5.6, but when updated to PHP7, I get the following fatal message and the white screen of death.</p>
  
  <blockquote>
    <p>Fatal error: Uncaught Error: Call to undefined function mysql_connect() in /home/s7280o8m/public_html/wp-includes/wp-db.php:1568 Stack trace: #0 /home/s7280o8m/public_html/wp-includes/wp-db.php(658): wpdb->db_connect() #1 /home/s7280o8m/public_html/wp-includes/load.php(404): wpdb->__construct('s7280o8m_wp891', 'K(p64@S137', 's7280o8m_wp891', 'localhost') #2 /home/s7280o8m/public_html/wp-settings.php(106): require_wp_db() #3 /home/s7280o8m/public_html/wp-config.php(90): require_once('/home/s7280o8m/...') #4 /home/s7280o8m/public_html/wp-load.php(37): require_once('/home/s7280o8m/...') #5 /home/s7280o8m/public_html/wp-blog-header.php(13): require_once('/home/s7280o8m/...') #6 /home/s7280o8m/public_html/index.php(17): require('/home/s7280o8m/...') #7 {main} thrown in /home/s7280o8m/public_html/wp-includes/wp-db.php on line 1568</p>
  </blockquote>
  
  <p>F.Y.I :</p>
  
  <ol>
  <li><p>Ran the PHP7 compatibly test and the plugins + theme were all good.</p></li>
  <li><p>In trying solve the fatal error, I have deactivated all the plugins (one by one) and then re-activate (one by one), plus changed the theme, but the problem still persists. </p></li>
  </ol>
  
  <p>Really would appreciate any help on this.</p>