A lot of errors today due to errors in Closure$RecentChange::save causing alarms on #wikimedia-operations:
exception.message Cannot access the database: Unknown error (10.64.48.150) --> db1084, commonswiki #0 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/loadbalancer/LoadBalancer.php(995): Wikimedia\Rdbms\Database->reportConnectionError(string) #1 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/loadbalancer/LoadBalancer.php(666): Wikimedia\Rdbms\LoadBalancer->reportConnectionError() #2 /srv/mediawiki/php-1.30.0-wmf.7/includes/GlobalFunctions.php(3100): Wikimedia\Rdbms\LoadBalancer->getConnection(integer, array, boolean) #3 /srv/mediawiki/php-1.30.0-wmf.7/includes/user/User.php(783): wfGetDB(integer) #4 /srv/mediawiki/php-1.30.0-wmf.7/includes/user/User.php(402): User::idFromName(string, integer) #5 /srv/mediawiki/php-1.30.0-wmf.7/includes/user/User.php(2232): User->load() #6 /srv/mediawiki/php-1.30.0-wmf.7/includes/WatchedItemStore.php(736): User->getId() #7 /srv/mediawiki/php-1.30.0-wmf.7/includes/mail/EmailNotification.php(135): WatchedItemStore->updateNotificationTimestamp(User, Title, string) #8 /srv/mediawiki/php-1.30.0-wmf.7/includes/changes/RecentChange.php(369): EmailNotification->notifyOnPageChange(User, Title, string, string, integer, integer, string) #9 [internal function]: Closure$RecentChange::save(integer) #10 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/database/Database.php(2657): call_user_func_array(Closure$RecentChange::save;1387, array) #11 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/database/Database.php(2891): Wikimedia\Rdbms\Database->runOnTransactionIdleCallbacks(integer) #12 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/database/Database.php(756): Wikimedia\Rdbms\Database->commit(string, string) #13 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1084): Wikimedia\Rdbms\Database->close() #14 [internal function]: Closure$Wikimedia\Rdbms\LoadBalancer::closeAll(Wikimedia\Rdbms\DatabaseMysqli) #15 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1485): call_user_func_array(Closure$Wikimedia\Rdbms\LoadBalancer::closeAll;1052, array) #16 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1085): Wikimedia\Rdbms\LoadBalancer->forEachOpenConnection(Closure$Wikimedia\Rdbms\LoadBalancer::closeAll;1052) #17 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1076): Wikimedia\Rdbms\LoadBalancer->closeAll() #18 /srv/mediawiki/php-1.30.0-wmf.7/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1665): Wikimedia\Rdbms\LoadBalancer->disable() #19 [internal function]: Wikimedia\Rdbms\LoadBalancer->__destruct() #20 {main}