在Ubuntu 20.04上运行DigitalOcean LAMP Stack（1GB VPS），上传媒体文件时，我在WordPress中收到间歇性的“Error establshing a database connection”错误。
第一个月
发生此问题时，MySQL日志重复打印以下内容，此后没有任何其他内容：

2020-12-19T12:14:43.708558Z 0 [System] [MY-013602] [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel.
    2020-12-19T12:14:43.992793Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.22-0ubuntu0.20.04.3'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  (Ubuntu).
    2020-12-19T12:14:59.498001Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.22-0ubuntu0.20.04.3) starting as process 190645
    2020-12-19T12:14:59.512933Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
    2020-12-19T12:15:00.093514Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
    2020-12-19T12:15:00.448326Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '127.0.0.1' port: 33060, socket: /var/run/mysqld/mysqlx.sock
    2020-12-19T12:15:00.524531Z 0 [System] [MY-010229] [Server] Starting XA crash recovery...
    2020-12-19T12:15:00.543848Z 0 [System] [MY-010232] [Server] XA crash recovery finished.
    2020-12-19T12:15:00.652394Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.

我尝试了这个修复：WordPress database error MySQL server has gone away for query
网站仍然显示错误，所以我想我应该重新启动MySQL，但它不会重新启动。
对于sudo service MySQL start，我得到
Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details.
运行第一个命令：

● mysql.service - MySQL Community Server
 Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
 Active: failed (Result: exit-code) since Sat 2020-12-19 12:45:50 UTC; 1min 3s ago
Process: 192068 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
Process: 192076 ExecStart=/usr/sbin/mysqld (code=exited, status=1/FAILURE)
Main PID: 192076 (code=exited, status=1/FAILURE)
 Status: "Server startup in progress"
  Error: 13 (Permission denied)

运行第二个命令

Hint: You are currently not seeing messages from other users and the system.
  Users in groups 'adm', 'systemd-journal' can see all messages.
  Pass -q to turn off this notice.
 -- Defined-By: systems
 -- Support: http://www.ubuntu.com/support
 --
 -- A start job for unit UNIT has finished successfully.
 --
 -- The job identifier is 8.
 Dec 19 12:13:48 server systemd[189372]: Listening on REST API socket for snapd user session agent.
 -- Subject: A start job for unit UNIT has finished successfully
 -- Defined-By: systems
 -- Support: http://www.ubuntu.com/support
 --
 -- A start job for unit UNIT has finished successfully.
 --
 -- The job identifier is 11.
 Dec 19 12:13:48 server systemd[189372]: Listening on D-Bus User Message Bus Socket.
 -- Subject: A start job for unit UNIT has finished successfully
 -- Defined-By: systems
 -- Support: http://www.ubuntu.com/support
 --
 -- A start job for unit UNIT has finished successfully.
 --
 -- The job identifier is 9.
 Dec 19 12:13:48 server systemd[189372]: Reached target Sockets.
 -- Subject: A start job for unit UNIT has finished successfully
 -- Defined-By: systems
 -- Support: http://www.ubuntu.com/support
 --
 -- A start job for unit UNIT has finished successfully.
 --
 -- The job identifier is 5.
 Dec 19 12:13:48 server systemd[189372]: Reached target Basic System.
 -- Subject: A start job for unit UNIT has finished successfully
 -- Defined-By: systems
 -- Support: http://www.ubuntu.com/support
 --
 -- A start job for unit UNIT has finished successfully.
 --
 -- The job identifier is 2.
 Dec 19 12:13:48 server systemd[189372]: Reached target Main User Target.
 -- Subject: A start job for unit UNIT has finished successfully
 -- Defined-By: systems
 -- Support: http://www.ubuntu.com/support
 --
 -- A start job for unit UNIT has finished successfully.
 --
 -- The job identifier is 1.
 Dec 19 12:13:48 server systemd[189372]: Startup finished in 168ms.
 -- Subject: User manager start-up is now complete
 -- Defined-By: systems
 -- Support: http://www.ubuntu.com/support
 --
 -- The user manager instance for user 1000 has been started. All services queued
 -- for starting have been started. Note that other services might still be starting
 -- up or be started at any later time.
 --
 -- Startup of the manager took 168965 microseconds.
 Dec 19 12:15:07 server sudo[190726]: pam_unix(sudo:auth): Couldn't open /etc/securetty: No such file or directory
 Dec 19 12:15:09 server sudo[190726]: pam_unix(sudo:auth): Couldn't open /etc/securetty: No such file or directory
 Dec 19 12:30:17 server sudo[191518]: pam_unix(sudo:auth): Couldn't open /etc/securetty: No such file or directory
 Dec 19 12:30:19 server sudo[191518]: pam_unix(sudo:auth): Couldn't open /etc/securetty: No such file or directory
 Dec 19 12:32:25 server sudo[191686]: pam_unix(sudo:auth): Couldn't open /etc/securetty: No such file or directory
 Dec 19 12:32:27 server sudo[191686]: pam_unix(sudo:auth): Couldn't open /etc/securetty: No such file or directory

第一个错误导致我这样：https://askubuntu.com/questions/1228827/mysql-error-13-permission-denied
但是MySQL已经拥有/var/lib/mysql。/usr/sbin/mysqld的所有者是root。这与MySQL正常工作的另一个服务器上的所有者相同。我真的应该更改它吗？