.NET: Why does MySql.Data 6.10.9 throw "The given key was not present in the dictionary" when executing a query against MySQL 8?

We are working with an older .NET Framework version and have installed the MySql.Data.6.10.9 package for testing.

The sample code successfully connects to MySQL v8.0.32, but when executing SELECT VERSION(); it returns the error: "Error executing query: The given key was not present in the dictionary."

Below is the test output and the connection strings we tried:

• server=192.168.56.5;uid=root;port=3306;database=test-source;pwd=mysql_root_password
• server=192.168.56.5;uid=root;port=3306;database=test-source;charset=utf8mb4;pwd=mysql_root_password

Both connection strings produce the same error. We also reviewed a related discussion on Stack Overflow, but it did not resolve our issue:

• https://stackoverflow.com/questions/41930040/net-mysql-error-the-given-key-was-not-present-in-the-dictionary#:~:text=For%20anyone%20with%20the%20error,the%20connector%20should%20solve%20it

Below is the full sample source code:

CSHARPCopied
using System;
using MySql.Data.MySqlClient;

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine(".Net version: " + Environment.Version.ToString());
        string connectionString = "server=192.168.56.5;uid=root;port=3306;database=test-source;pwd=mysql_root_password";

        try
        {
            using (var connection = new MySqlConnection(connectionString))
            {
                Console.WriteLine("Attempting to open connection...");
                connection.Open();

                if (connection.State == System.Data.ConnectionState.Open)
                {
                    Console.WriteLine("Connection successful!");

                    // Retrieve MySQL version
                    try
                    {
                        string query = "SELECT VERSION();";
                        using (var command = new MySqlCommand(query, connection))
                        {
                            string version = command.ExecuteScalar().ToString();
                            Console.WriteLine("MySQL Version: " + version);
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine("Error executing query: " + ex.Message);
                    }

                }
                else
                {
                    Console.WriteLine("Failed to open the connection.");
                }
            }
        }
        catch (MySqlException ex)
        {
            Console.WriteLine("MySQL Exception: " + ex.Message);
        }
        catch (Exception ex)
        {
            Console.WriteLine("General Exception: " + ex.Message);
        }
    }

}

What might be causing this error and how can it be resolved given our legacy .NET constraints?