Moved to New Server, Same Domain Name, Error Establishing Database Connection

Hi all.. I just moved to a new server/host.

I first took a back up of my public_html folder on my ftp server, then I created a back up of my mysql database in phpmyadmin.

I added my url to the new host, and uploaded all files (after installing a new wordpress, editing the wp-config.php and uploading my .sql file to phpmyadmin).

Still, for some reason, I’m getting these errors:

Warning: Cannot modify header information - headers already sent by (output started at /home/dcbs/public_html/wp-content/plugins/leaguemanager/lib/widget.php:677) in /home/dcbs/public_html/wp-content/plugins/simplelogin/includes/wp-login-actions.php on line 65

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/dcbs/public_html/wp-content/plugins/leaguemanager/lib/widget.php:677) in /home/dcbs/public_html/wp-content/plugins/si-contact-form/si-contact-form.php on line 1138

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/dcbs/public_html/wp-content/plugins/leaguemanager/lib/widget.php:677) in /home/dcbs/public_html/wp-content/plugins/si-contact-form/si-contact-form.php on line 1138

What do I need to do?

My site is