MySQL PHP Incompatibility: Understanding the Connection Error and Resolution

Encountering the "OK packet 6 bytes shorter than expected" error when connecting to a remote MySQL database with PHP version 5.3.0 can be a puzzling issue. To resolve this problem, it is crucial to understand the underlying cause and apply the appropriate solution.

The error points to an incompatibility between the local PHP version and the remote MySQL server. PHP versions 5.3.0 and higher require that MySQL accounts have passwords hashed using the new MySQL authentication plugin. However, older MySQL versions like 5.0.22 may still use the old authentication method with 16-character passwords. This discrepancy leads to the error as PHP 5.3.0 fails to interpret the response from the MySQL server correctly.

To address this issue, there are two possible solutions:

• Set a New Password: For the account experiencing the error, use a MySQL client to execute the command "SET PASSWORD FOR 'username'@'hostmask' = PASSWORD('thepassword')" to generate a new hashed password. This will update the account's password to the new authentication format.
• Configure the MySQL Server: Alternatively, you can check if the MySQL server is configured to use the old authentication method by default. If so, you can modify the server settings to enforce the new authentication plugin and disallow old passwords.

To determine if the account is using an old 16-character password, execute the query:

SELECT
  Length(`Password`),
  Substring(`Password`, 1, 1)
FROM
  `mysql`.`user`
WHERE
  `user`='username'

On the problematic 5.0.22 server, replacing 'username' with the account in question. If the result shows a password length of 16 and the first character is a hexadecimal digit (0-9 or A-F), it indicates an old password.

By understanding the underlying cause and applying the appropriate solution, you can resolve the MySQL PHP incompatibility and establish a successful connection to the remote database.