MySQL error 3168 (ER_SERVER_ISNT_AVAILABLE) signals that the client cannot reach the MySQL server process at the requested host and port.
MySQL Error 3168 ER_SERVER_ISNT_AVAILABLE means the client cannot reach the MySQL server. Check that mysqld is running, verify host, port, and firewall rules, then retry the connection.
ER_SERVER_ISNT_AVAILABLE
Error 3168 appears when your MySQL client attempts a handshake but receives no response because the mysqld process is unreachable. The error was introduced in MySQL 5.7.9 and maps to SQLSTATE HY000.
The message usually surfaces in logs or client output during connection attempts, batch jobs, or application startup. Resolving it quickly is critical to restore database availability and avoid cascading application failures.
Most occurrences stem from the MySQL service not running, a crashed daemon, or an incorrect socket, host, or port configuration. Network issues, firewalls, and resource exhaustion can also block communication.
In containerized or cloud setups, delayed startup sequencing, missing health checks, or misconfigured service discovery often trigger the error.
Start by confirming that mysqld is active. On Linux, run systemctl status mysqld or mysqld_safe. If stopped, start it and watch the error log for crashes.
Next, validate connection parameters. Ensure client and server agree on host, port, and socket. Test with mysql -h 127.0.0.1 -P 3306 -u root.
Inspect firewalls and security groups to confirm TCP port 3306 is open between client and server.
After server reboot, MySQL may fail to start because of corrupted innodb files. Restore from backup or run innodb_recovery_mode.
In Docker Compose stacks, dependent containers can try connecting before MySQL is ready. Add healthcheck and depends_on clauses to delay startup.
Enable MySQL as a managed service or use process supervisors so mysqld restarts automatically after crashes.
Monitor port availability and service health with Prometheus or Galaxy’s query runner to receive alerts before clients fail.
Error 2003 (Can't connect to MySQL server) is thrown on the client side when the host or port is unreachable. Follow similar troubleshooting steps.
Error 1045 (Access denied) indicates the server is reachable but authentication failed. Verify user credentials instead of network paths.
Galaxy’s connection manager stores host, port, and SSL details centrally, reducing misconfigurations that cause ER_SERVER_ISNT_AVAILABLE. Built-in health checks warn you when the database becomes unreachable, allowing proactive fixes.
The daemon crashed or was never started, leaving no listener on the configured port.
Applications point to an outdated DNS entry or a non-default port.
Security layers deny incoming traffic to port 3306.
The server is out of file descriptors or RAM, causing mysqld to exit unexpectedly.
Client-side error when host or port is unreachable.
Authentication failure after connection is established.
Unix socket file missing or misconfigured.
Yes, it usually indicates the server process is not accepting connections on the specified endpoint.
If the server is running but blocked by a firewall, adjusting rules can restore access without a restart.
No. Credential issues raise error 1045, while 3168 appears when the server is unreachable.
Galaxy checks connection health before each query and alerts you if the server is offline, letting you act early.
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