I'm trying to get the hang of using custom session handlers to store session data in a MySQL database. However, I keep getting the following warning: mysql_close(): supplied argument is not a valid MySQL-Link resource Here's the code I'm using, which I got from here: function _open(){ global $_sess_db; $_sess_db = mysql_connect("localhost", "root", "******"); if ($_sess_db) { return mysql_select_db('style', $_sess_db); } return false; } function _close(){ global $_sess_db; return mysql_close($_sess_db); //error happens here } The full text of the error message ultimately points to the final "return mysql_close($_sess_db);" line. I can confirm that the mysql_connect info does in fact work, and I do have the rest of the session handler functions defined as well. And in case it helps, I get these errors immediately upon page load, without actually calling any of the session handler functions, and without having any current sessions open.