Some releases of MySQL introduce changes to the structure of the system tables in the mysql database to add new privileges or support new features. When you update to a new version of MySQL, you should update your system tables as well to make sure that their structure is up to date. Otherwise, there might be capabilities that you cannot take advantage of. First, make a backup of your mysql database, and then use the following procedure.

On Unix or Unix-like systems, update the system tables by running the mysql_fix_privilege_tables script:

shell> mysql_fix_privilege_tables

You must run this script while the server is running. It attempts to connect to the server running on the local host as root. If your root account requires a password, indicate the password on the command line. For MySQL 4.1 and up, specify the password like this:

shell> mysql_fix_privilege_tables --password=root_password

Prior to MySQL 4.1, specify the password like this:

shell> mysql_fix_privilege_tables root_password

The mysql_fix_privilege_tables script performs any actions necessary to convert your system tables to the current format. You might see some Duplicate column name warnings as it runs; you can ignore them.

After running the script, stop the server and restart it so that it uses any changes that were made to the system tables.

On Windows systems, there isn't an easy way to update the system tables until MySQL 4.0.15. From version 4.0.15 on, MySQL distributions include a mysql_fix_privilege_tables.sql SQL script that you can run using the mysql client. For example, if your MySQL installation is located at C:\Program Files\MySQL\MySQL Server 4.1, the commands look like this:

C:\> cd "C:\Program Files\MySQL\MySQL Server 4.1"
C:\> bin\mysql -u root -p mysql
mysql> SOURCE scripts/mysql_fix_privilege_tables.sql

The mysql command will prompt you for the root password; enter it when prompted.

If your installation is located in some other directory, adjust the path names appropriately.

As with the Unix procedure, you might see some Duplicate column name warnings as mysql processes the statements in the mysql_fix_privilege_tables.sql script; you can ignore them.

After running the script, stop the server and restart it.