Unable to Connect to MySQL Hosts in C#: Troubleshooting and Resolution

When attempting to connect to a MySQL database through C#, you may encounter the error message "Unable to connect to any of the specified MySQL hosts." This issue can arise due to several reasons.

To address this error, it is important to first ensure that the parameters specified in the connection string are valid and in the correct order. The recommended format for the connection string is as follows:

Server=myServerAddress;Port=1234;Database=myDataBase;Uid=myUsername;Pwd=myPassword;

In your case, the connection string has the parameter "server" specified as "127.0.0.1." While this is a valid IP address for the local machine, it is recommended to use the hostname "localhost" instead. This is because some versions of MySQL have issues with IP addresses in the connection string.

Additionally, the "database" parameter should be specified with the database name to which you wish to connect. The "uid" and "pwd" parameters represent the username and password for MySQL authentication.

If the issue persists even after ensuring the parameters are correct, you may try setting the "Pooling" property of the MySqlConnection object to false. This will disable connection pooling, which can resolve certain connection issues.

MySqlConnection mysqlConn=new MySqlConnection("server=localhost;uid=root;port=3306;pwd=master;database=patholabs;");
mysqlConn.Pooling = false;
mysqlConn.Open();

In some cases, the issue may be related to the MySQL server itself. Ensure that the MySQL server is running and accepting connections on the specified port. You can verify this by attempting to connect to the database using the MySQL command-line client or a GUI tool such as MySQL Workbench.

If you are still unable to connect, it is worth checking the event logs on your local machine or the MySQL server to see if any additional information is available regarding the connection failure.