Uncaught exception thrown in shutdown function.

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] => 7699156966827cd1bee9d91.61568507 ) in lock_release_all() (line 269 of /home/mod/web/mod.gov.mm/public_html/includes/lock.inc).