Example Code (Node.js with Sequelize and mysql2)

• SequelizeConnectionError: This indicates an error establishing a connection between your Node.js application (using Sequelize) and the MySQL/MariaDB database server.
• Client does not support authentication protocol requested by server: The core issue is a compatibility mismatch between the authentication protocol required by the MariaDB server and the protocol supported by the MariaDB client library you're using in your Node.js application.

Possible Causes:

• Outdated MariaDB Client Library: The most likely scenario is that the MariaDB client library (e.g., mysql2) in your Node.js project is outdated. Newer MariaDB servers might use more secure authentication protocols that older client libraries don't understand.
• Incompatible MariaDB Server Configuration: In rare cases, your MariaDB server might be configured to enforce a specific authentication protocol that's not the default (like caching_sha2_password).

Solutions:

1. Upgrade MariaDB Client Library: This is the recommended solution in most cases. Here's a general process:
   • Identify the MariaDB client library you're using (e.g., mysql2).
   • Check the library's documentation for upgrade instructions. Usually, it involves using a package manager like npm to update the package to the latest version:

     npm install mysql2@latest
     

2. Review MariaDB Server Configuration (if necessary): If upgrading the client library doesn't resolve the issue, consult your MariaDB server's documentation to verify the authentication protocol settings. You might need to adjust them to match what your client library supports. However, proceed with caution as this might involve security implications.

Additional Tips:

• Check Sequelize and Node.js Versions: Ensure you're using compatible versions of Sequelize and Node.js that work well with the MariaDB client library version. Refer to their respective documentation for compatibility information.
• Clear Node.js Cache: In some cases, clearing the Node.js cache might help:

  npm cache clean --force
  

Example Code (Node.js with Sequelize and mysql2)

const Sequelize = require('sequelize');

// Assuming you have MariaDB credentials and database details
const sequelize = new Sequelize({
  dialect: 'mysql', // Specify dialect as mysql
  host: 'your_mariadb_host',
  port: 3306, // Default MariaDB port
  username: 'your_username',
  password: 'your_password',
  database: 'your_database_name',
  pool: {
    max: 5, // Maximum number of connection pool connections
    min: 0, // Minimum number of connection pool connections
    acquire: 30000, // Timeout for acquiring a connection from the pool
    idle: 10000, // Timeout for a connection to remain idle in the pool
  },
});

(async () => {
  try {
    await sequelize.authenticate();
    console.log('Connection to MariaDB has been established successfully.');
  } catch (error) {
    console.error('Unable to connect to MariaDB:', error);
  }
})();

Explanation:

1. Import Sequelize: Import the Sequelize library using require('sequelize').
2. Database Credentials: Replace placeholders like your_mariadb_host, your_username, your_password, and your_database_name with your actual MariaDB connection details.
3. Connection Pool: The pool section configures a connection pool for Sequelize, which helps manage database connections efficiently.
4. sequelize.authenticate(): This function attempts to establish a connection to the MariaDB database.
5. Error Handling: The code includes an async/await block to handle potential connection errors.

Upgrading the MariaDB Client Library:

If you encounter the "SequelizeConnectionError", you can upgrade the mysql2 library using npm:

npm install mysql2@latest

This approach involves changing settings on the MariaDB server to use a less secure authentication protocol that your outdated client library understands. However, this is generally not recommended as it can weaken the security of your database. It's best to prioritize keeping your client library up-to-date for compatibility and security improvements.

Here's a general outline, but consult your MariaDB server documentation for specific instructions:

• Connect to MariaDB Server: Use the mysql command-line tool to connect to your MariaDB server as an administrator.
• Change Authentication Plugin: Execute a query like ALTER USER 'your_username'@'localhost' IDENTIFIED WITH mysql_native_password BY 'your_password'. This ensures the user specified can use the mysql_native_password plugin, which is a more basic authentication method.
• Restart MariaDB Server: This might be necessary for the changes to take effect (refer to your server's documentation).

Using a Different Client Library (Consider Trade-offs):

• If upgrading the mysql2 library isn't feasible due to project constraints, you could explore alternative MariaDB client libraries like tedious (for Microsoft SQL Server compatibility) or mariadb (specifically for MariaDB).
• However, evaluate the trade-offs before switching. These alternative libraries might have their own quirks or require additional configuration. Additionally, ensure the new library is actively maintained and has a good reputation.

Remember:

• Prioritize upgrading the client library if possible. It's the most secure and future-proof solution.
• Proceed with caution when modifying server configuration or switching client libraries. Make sure you understand the security implications before making changes.
• Consult documentation for specific instructions related to your MariaDB server version and chosen client library (if applicable).