Why am I Getting 'com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server' Error?

"com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server" Troubleshooting

This error message indicates an issue establishing a connection to a MySQL database server. The Java code you provided utilizes an outdated version of MySQL Connector/J, which may not be compatible with MySQL 8.0.

To resolve this issue, upgrade to MySQL Connector/J 5.1.46 or 8.0.11 (or a newer version). Here's the revised code:

import com.mysql.cj.jdbc.Driver;

public class Main {
    public static void main(String[] args) {
        try {
            Driver sqlDriver = new Driver();
            DriverManager.registerDriver(sqlDriver);
            Connection sqlConnection = DriverManager.getConnection("jdbc:mysql://localhost:3306/?user=root", "root", "root");
            System.out.println("Connection established successfully");
            sqlConnection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Causes of this Issue

• Compatibility Problems: Older versions of MySQL Connector/J may not fully support newer versions of MySQL servers, leading to connection issues.
• Incorrect Configuration: Check that your MySQL server is running on the specified port (3306 in the code) and that you are providing the correct credentials for the database connection.
• Firewall or Network Issues: Ensure that your firewall is not blocking the connection and that your network allows connections to the MySQL server.

Additional Tips

• Verify MySQL Server Version: Run SHOW VARIABLES LIKE 'version'; in MySQL command line to confirm your MySQL server version.
• Check MySQL Connector/J Compatibility: Visit the MySQL website to determine the compatible Connector/J version for your MySQL server.
• Look for Errors in the Stack Trace: The stack trace often provides more detail about the underlying cause of the connection failure. Check for specific errors or messages that may indicate a specific problem.

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