If the MySQL server cannot find the mysql privileges database or other critical files, you may see these messages:

System error 1067 has occurred.
Fatal error: Can't open privilege tables: Table 'mysql.host' doesn't exist

These messages often occur when the MySQL base or data directories are installed in different locations than the default locations (C:\Program Files\MySQL\MySQL Server 5.5 and C:\Program Files\MySQL\MySQL Server 5.5\data, respectively).

This situation may occur when MySQL is upgraded and installed to a new location, but the configuration file is not updated to reflect the new location. In addition, there may be old and new configuration files that conflict. Be sure to delete or rename any old configuration files when upgrading MySQL.

If you have installed MySQL to a directory other than C:\Program Files\MySQL\MySQL Server 5.5, you need to ensure that the MySQL server is aware of this through the use of a configuration (my.ini) file. The my.ini file needs to be located in your Windows directory, typically C:\WINDOWS. You can determine its exact location from the value of the WINDIR environment variable by issuing the following command from the command prompt:

C:\> echo %WINDIR%

An option file can be created and modified with any text editor, such as Notepad. For example, if MySQL is installed in E:\mysql and the data directory is D:\MySQLdata, you can create the option file and set up a [mysqld] section to specify values for the basedir and datadir options:

[mysqld]
# set basedir to your installation path
basedir=E:/mysql
# set datadir to the location of your data directory
datadir=D:/MySQLdata

Note that Windows path names are specified in option files using (forward) slashes rather than backslashes. If you do use backslashes, double them:

[mysqld]
# set basedir to your installation path
basedir=C:\\Program Files\\MySQL\\MySQL Server 5.5
# set datadir to the location of your data directory
datadir=D:\\MySQLdata

The rules for use of backslash in option file values are given in Section 4.2.3.3, “Using Option Files”.

If you change the datadir value in your MySQL configuration file, you must move the contents of the existing MySQL data directory before restarting the MySQL server.

See Section 2.3.5.2, “Creating an Option File”.

If you reinstall or upgrade MySQL without first stopping and removing the existing MySQL service and install MySQL using the MySQL Configuration Wizard, you may see this error:

Error: Cannot create Windows service for MySql. Error: 0

This occurs when the Configuration Wizard tries to install the service and finds an existing service with the same name.

One solution to this problem is to choose a service name other than mysql when using the configuration wizard. This enables the new service to be installed correctly, but leaves the outdated service in place. Although this is harmless, it is best to remove old services that are no longer in use.

To permanently remove the old mysql service, execute the following command as a user with administrative privileges, on the command-line:

C:\> sc delete mysql
[SC] DeleteService SUCCESS

If the sc utility is not available for your version of Windows, download the delsrv utility from http://www.microsoft.com/windows2000/techinfo/reskit/tools/existing/delsrv-o.asp and use the delsrv mysql syntax.