Recently, I have often been getting the "Error:MySQL server has gone away" message after I enabled the multiple-user access in front web service. Here is logs. . . . Upper Omission . . . 2017-04-10 21:15:22.881 [INFO][socketio.js] socket disconnect 2017-04-10 21:15:23.858 [INFO][socketio.js] socket connection 2017-04-10 21:36:07.635 [INFO][socketio.js] socket disconnect 2017-04-10 21:36:16.635 [INFO][socketio.js] socket disconnect 2017-04-10 21:46:12.254 [INFO][socketio.js] socket disconnect 2017-04-10 21:46:12.255 [INFO][socketio.js] socket disconnect events.js:160 throw er; // Unhandled 'error' event ^ Error: MySQL server has gone away at Error (native) At this time, I have checked the status of mariadb server. Please, see a time stampe information from the below mariadb's status. As we can see, the mariadb server was not stopped or not restarted. root@mytizen:~# systemctl status mysql * mysql.service - LSB: Start and stop the mysql database server daemon Loaded: loaded (/etc/init.d/mysql; bad; vendor preset: enabled) Active: active (running) since 2017-04-10 15:35:34 KST; 15h ago Docs: man:systemd-sysv-generator(8) Process: 1982 ExecStart=/etc/init.d/mysql start (code=exited, status=0/SUCCESS) Tasks: 28 Memory: 131.6M CPU: 29.563s CGroup: /system.slice/mysql.service ├─2544 /bin/bash /usr/bin/mysqld_safe ├─2691 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib/mysql/plugin --user=my └─2692 logger -t mysqld -p daemon error 4월 10 15:35:31 mytizen mysqld[2692]: 170410 15:35:31 [Note] InnoDB: 128 rollback segment(s) are active. 4월 10 15:35:31 mytizen mysqld[2692]: 170410 15:35:31 [Note] InnoDB: Waiting for purge to start 4월 10 15:35:31 mytizen mysqld[2692]: 170410 15:35:31 [Note] InnoDB: Percona XtraDB (http://www.percona.com) 5.6.34-79 4월 10 15:35:31 mytizen mysqld[2692]: 170410 15:35:31 [Note] Plugin 'FEEDBACK' is disabled. 4월 10 15:35:31 mytizen mysqld[2692]: 170410 15:35:31 [Note] Server socket created on IP: '127.0.0.1'. 4월 10 15:35:33 mytizen mysqld[2692]: 170410 15:35:33 [Note] /usr/sbin/mysqld: ready for connections. 4월 10 15:35:33 mytizen mysqld[2692]: Version: '10.0.29-MariaDB-0ubuntu0.16.04.1' socket: '/var/run/mysqld/mysqld.sock 4월 10 15:35:34 mytizen mysql[1982]: ...done. 4월 10 15:35:34 mytizen systemd[1]: Started LSB: Start and stop the mysql database server daemon. 4월 10 15:35:34 mytizen mysql[1982]: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO) root@mytizen:~# root@mytizen:~# ------------------- root@mytizen:~# ls -al /var/run/mysqld/mysqld.sock srwxrwxrwx 1 mysql mysql 0 4 10 15:35 /var/run/mysqld/mysqld.sock After digging the operation functions from the mariadb source ( https://github.com/MariaDB/server), I could get some hints where the issue was generated. For example, a) storage/spider/spd_trx.cc (!conn->disable_reconnect) https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_... b) storage/cassandra/ha_cassandra.cc Anyone who experience a similar issue such as "Error: MySQL server has gone away" message? -- http://leemgs.fedorapeople.org Don't try to avoid pain if you fail. If you decided to face the challenges in life, you can gain a lot by giving your best. Cheolsang Jeong's Book & life --