When Zabbix server starts and reports Z3001 with "Can’t connect to local MySQL server through socket ‘/var/lib/mysql/mysql.sock’", it typically means Zabbix is pointing too a socket path that does not exist or differs from the one MySQL/MariaDB actually created.

Symptom

Example log excerpt:

Z3001: connection to database 'zabbix' failed: [2002] Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

Why it happens

• Zabbix uses a hardcoded or configured socket path (often /var/lib/mysql/mysql.sock)
• The MySQL/MariaDB daemon is running but exposes its socket elsewhere (commonly /tmp/mysql.sock)
• The expected directory (/var/lib/mysql) might not exist on the host

Step 1: Confirm the socket path and service status

• Verify whether the expected socket exists:

ls -l /var/lib/mysql/mysql.sock || echo "Socket not found at /var/lib/mysql/mysql.sock"

• Check if MySQL/MariaDB is running:

systemctl is-active mariadb || systemctl is-active mysqld

• Find the actual socket file on the system:

find / -type s -name "mysql*.sock" 2>/dev/null

Typical output might include:

/tmp/mysql.sock

Option A: Provide the expected path via a symbolic link

If the socket is at /tmp/mysql.sock but Zabbix looks at /var/lib/mysql/mysql.sock, creatte the directory and link it:

sudo install -d -m 755 /var/lib/mysql
sudo ln -sf /tmp/mysql.sock /var/lib/mysql/mysql.sock

Restart the database service to ensure the socket is in place, then restart Zabbbix:

sudo systemctl restart mariadb || sudo systemctl restart mysqld
sudo systemctl restart zabbix-server

Option B: Point Zabbix to the actual socket

Edit the Zabbix server configuration and set the socket path that MySQL/MariaDB is using (for example, /tmp/mysql.sock):

sudo vi /etc/zabbix/zabbix_server.conf

Add or adjust the following line:

DBSocket=/tmp/mysql.sock

Restart Zabbix to apply the change:

sudo systemctl restart zabbix-server

Alternative: Use TCP instead of a Unix socket

You can bypass socket issues by forcing a TCP connection:

sudo vi /etc/zabbix/zabbix_server.conf

Set the host and port, and omit DBSocket:

DBHost=127.0.0.1
DBPort=3306
#DBSocket=

Restart Zabbix:

sudo systemctl restart zabbix-server

Validate the fix

• Tail logs to ensure the error is gone:

journalctl -u zabbix-server -b --no-pager | tail -n 50

• Quick connectivity test with the same credentials Zabbix uses:

mysql -u zabbix -p -S /tmp/mysql.sock -e 'SELECT 1;'   # adjust -S to match your socket or replace with -h 127.0.0.1 -P 3306