Wordpress Code modify it accordingly to the documentation of WordPress

Wordpress / Custom add on dose not work properly after wordpress was updated . _______________________________________________________________ Hi we have a wordpress site that uses a custom add on that was created 4 years ago . after yesterdays wordpress update, the addon is not working correctly. Job Wordpress Code modify it accordingly to the documentation of WordPress [login to view URL] _________________________________________________________________ Our Support team checked the problem and wrote us the following. The issue which you are experiencing is not related to the php version applied for your domain "[login to view URL]". The following warnings: Warning: mysql_query(): Access denied for user ''@'localhost' (using password: NO) in /home/studiologin/public_html/[login to view URL] on line 843 Warning: mysql_query(): A link to the server could not be established in /home/studiologin/public_html/[login to view URL] on line 843 Warning: mysql_fetch_array() expects parameter 1 to be resource, boolean given in /home/studiologin/public_html/[login to view URL] on line 844 Warning: Cannot modify header information - headers already sent by (output started at /home/studiologin/public_html/[login to view URL]) in /home/studiologin/public_html/wp-includes/[login to view URL] on line 1216 are being generated because there are changes in the "wpdb" class and the way the queries of the custom modules should be executed. You can learn more about the "wpdb" via the following link: [login to view URL] Please revise the your code and modify it accordingly to the documentation of WordPress, so you could resolve the experienced issue. ________________________________________________________________ We need somene that knows how to config Wordpress Code modify it accordingly to the documentation of WordPress Thanks