Additional uncaught exception thrown while handling exception.

<h1>Additional uncaught exception thrown while handling exception.</h1><h2>Original</h2><p>PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT r.rid AS rid, r.name AS name
FROM 
{role} r
ORDER BY weight ASC, name ASC; Array
(
)
 in user_roles() (line 2938 of /var/www/html/root/servsafe/modules/user/user.module).</p><h2>Additional</h2><p>PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT expire, value FROM {semaphore} WHERE name = :name; Array
(
    [:name] =&amp;gt; rules_get_cacherules_event_whitelist
)
 in lock_may_be_available() (line 167 of /var/www/html/root/servsafe/includes/lock.inc).</p><hr /><h1>Uncaught exception thrown in shutdown function.</h1><p>PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: DELETE FROM {semaphore} 
WHERE  (value = :db_condition_placeholder_0) ; Array
(
    [:db_condition_placeholder_0] =&amp;gt; 3945524586392d282a820c9.52747716
)
 in lock_release_all() (line 269 of /var/www/html/root/servsafe/includes/lock.inc).</p><hr />