Database error in vBulletin :

mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead
/home/kenan/public_html/ebook/includes/class_core.php on line 312

MySQL Error   : 
Error Number  : 
Request Date  : Wednesday, December 30th 2015 @ 09:55:28 AM
Error Date    : Wednesday, December 30th 2015 @ 09:55:28 AM
Script        : http://site.com/install/install.php?step=3
Referrer      : http://site.com/install/install.php?step=2
IP Address    : 78.166.59.174
Username      : 
Classname     : vB_Database
MySQL Version :