Error message

• Deprecated function: session_set_save_handler(): Providing individual callbacks instead of an object implementing SessionHandlerInterface is deprecated in drupal_session_initialize() (line 245 of includes/session.inc).
• Warning: session_set_save_handler(): Session save handler cannot be changed after headers have already been sent in drupal_session_initialize() (line 245 of includes/session.inc).
• Warning: session_id(): Session ID cannot be changed after headers have already been sent in drupal_session_initialize() (line 269 of includes/session.inc).
• Warning: Cannot modify header information - headers already sent by (output started at /var/www/discuss/includes/errors.inc:29) in drupal_send_headers() (line 1558 of includes/bootstrap.inc).
• Warning: Cannot modify header information - headers already sent by (output started at /var/www/discuss/includes/errors.inc:29) in drupal_send_headers() (line 1558 of includes/bootstrap.inc).
• Warning: Cannot modify header information - headers already sent by (output started at /var/www/discuss/includes/errors.inc:29) in drupal_send_headers() (line 1558 of includes/bootstrap.inc).
• Warning: session_start(): Session cannot be started after headers have already been sent in Facebook->__construct() (line 60 of sites/all/libraries/facebook-php-sdk/src/facebook.php).
• Warning: Cannot modify header information - headers already sent by (output started at /var/www/discuss/includes/errors.inc:29) in drupal_send_headers() (line 1558 of includes/bootstrap.inc).
• Warning: Cannot modify header information - headers already sent by (output started at /var/www/discuss/includes/errors.inc:29) in drupal_send_headers() (line 1558 of includes/bootstrap.inc).
• Warning: Cannot modify header information - headers already sent by (output started at /var/www/discuss/includes/errors.inc:29) in drupal_send_headers() (line 1558 of includes/bootstrap.inc).
• Warning: Cannot modify header information - headers already sent by (output started at /var/www/discuss/includes/errors.inc:29) in drupal_send_headers() (line 1558 of includes/bootstrap.inc).