Error message

• Warning: Cannot modify header information - headers already sent by (output started at /var/www/web5/html/includes/common.inc:2694) in drupal_send_headers() (line 1224 of /var/www/web5/html/includes/bootstrap.inc).
• PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: INSERT INTO {watchdog} (uid, type, message, variables, severity, link, location, referer, hostname, timestamp) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7, :db_insert_placeholder_8, :db_insert_placeholder_9); Array ( [:db_insert_placeholder_0] => 0 [:db_insert_placeholder_1] => cron [:db_insert_placeholder_2] => %type: !message in %function (line %line of %file). [:db_insert_placeholder_3] => a:6:{s:5:"%type";s:12:"PDOException";s:8:"!message";s:303:"SQLSTATE[HY000]: General error: 2013 Lost connection to MySQL server during query: UPDATE {variable} SET value=:db_update_placeholder_0 WHERE ( (name = :db_condition_placeholder_0) ); Array ( [:db_update_placeholder_0] => i:1550585354; [:db_condition_placeholder_0] => update_last_check ) ";s:9:"%function";s:14:"variable_set()";s:5:"%file";s:41:"/var/www/web5/html/includes/bootstrap.inc";s:5:"%line";i:983;s:14:"severity_level";i:3;} [:db_insert_placeholder_4] => 3 [:db_insert_placeholder_5] => [:db_insert_placeholder_6] => http://infernal-majesty.com/avatar/58 [:db_insert_placeholder_7] => [:db_insert_placeholder_8] => 18.206.175.155 [:db_insert_placeholder_9] => 1550585354 ) in dblog_watchdog() (line 160 of /var/www/web5/html/modules/dblog/dblog.module).