Additional uncaught exception thrown while handling exception.

Original

PDOException: SQLSTATE[HY000] [2003] Can't connect to MySQL server on 'mysql.cals.arizona.edu' (111) in _registry_check_code() (line 3486 of /var/www/drupal/drupal-7.51/includes/bootstrap.inc).

Additional

PDOException: SQLSTATE[HY000] [2003] Can't connect to MySQL server on 'mysql.cals.arizona.edu' (111) in _registry_check_code() (line 3486 of /var/www/drupal/drupal-7.51/includes/bootstrap.inc).