Uncaught exception thrown in shutdown function.

PDOException: SQLSTATE[25006]: Read only sql transaction: 7 ERROR: cannot execute DELETE in a read-only transaction: DELETE FROM {semaphore} WHERE (value = :db_condition_placeholder_0) ; Array ( [:db_condition_placeholder_0] => 1251478369610b43bcd065c0.66693165 ) in lock_release_all() (line 269 of /var/ig/webcontent/drupal/includes/lock.inc).