Mail stuck in the queue in the server with Plesk: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (13)

Rangel Sardinha

Updated September 09, 2025 21:00

Plesk for Linux kb: technical ext: pes ABT: Group A

Applicable to:

Plesk for Linux

Symptoms

E-Mails are stuck in the queue with below messages in /var/log/maillog:

amavis[26892]: (26892-01) (!)connect_to_sql: unable to connect to DSN 'DBI:mysql:database=emailsecurity;host=localhost;port=3306': Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (13)
amavis[26892]: (26892-01) (!!)TROUBLE in process_request: connect_to_sql: unable to connect to any dataset at (eval 132) line 253.
amavis[26892]: (26892-01) (!)Requesting process rundown after fatal error
MariaDB upgrade has been performed recently on the server with SELinux enabled

Cause

MariaDB bug #MDEV-24941: SElinux incorrect label for server socket.

The SELinux context for the MariaDB socket file /var/lib/mysql/mysql.sock has been lost because of an upgrade to MariaDB version affected by the bug. This bug will be fixed in mysql-selinux-1.0.14

Resolution

To workaround the problem until the bug is resolved apply the following steps:

Connect to the server via SSH

Warning: On applying the following step the database server MariaDB will be restarted, which leads to a short inaccessibility of other Plesk related services and websites accessing the database

Run the following command:

# printf '%s\n' '[Service]' 'ExecStartPost=/sbin/restorecon /var/lib/mysql/mysql.sock' > /etc/systemd/system/mariadb.service.d/restorecon_socket.conf && systemctl daemon-reload && systemctl restart mariadb
Resend the stuck e-mails

The following alternative workarounds are also available:

Disable SELinux
Downgrade MariaDB server to version not affected by bug #MDEV-24941
Disable Amavis by disabling Plesk Email Security extension