Why Does MySQL Throw an 'Unknown Authentication Method' Remote Connection Error?

MySQL Remote Connection Error: "Unknown Authentication Method"

When attempting to establish a remote connection to a MySQL server from a local machine, you may encounter the following error:

Warning: PDO::__construct(): The server requested authentication method unknown to the client [mysql_old_password] in ...

SQLSTATE[HY000] [2054] The server requested authentication method unknown to the client

Understanding the Problem:

This error typically indicates an incompatibility between the password hashing methods used by the local and remote MySQL servers. MySQL versions prior to 4.1 utilized a 16-byte password hashing method, while versions 4.1 and above adopted a more secure 41-byte hashing method. If the local MySQL server is using the old hashing method but the remote server is using the new one, the connection attempt will fail with the "unknown authentication method" error.

Resolving the Issue:

To resolve this issue, you will need to update the password on the remote MySQL server to use the new 41-byte hashing format. Here's how to do it:

1. Connect to the Remote MySQL Server:

   mysql -u [username] -p[password]

2. Update the Password:

   ALTER USER [username] IDENTIFIED BY '[new_password]';

3. Grant Permissions:

   Ensure that the user has the necessary permissions to access the database:

   GRANT ALL PRIVILEGES ON [database_name].* TO [username]@'local_ip_address';

4. Reconnect:

   Try connecting to the remote MySQL server with the updated password:

   $dsn = 'mysql:host=184.173.209.193;dbname=my_db_name';
   $options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8',
   );
   
   try {
       $online_dbh = new PDO($dsn, 'myusername', 'new_password', $options);
       $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
       echo "Success!";
   } catch (PDOException $e) {
       echo $e->getMessage();
   }

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