MySQL 5.1 uses an authentication protocol based on a password hashing algorithm that is incompatible with that used by older (pre-4.1) clients. If you upgrade the server from 4.0, attempts to connect to it with an older client may fail with the following message:
mysqlClient does not support authentication protocol requested by server; consider upgrading MySQL client
To solve this problem, you should use one of the following approaches:
Upgrade all client programs to use a 4.1.1 or newer client library.
When connecting to the server with a pre-4.1 client program, use an account that still has a pre-4.1-style password.
Reset the password to pre-4.1 style for each user that
needs to use a pre-4.1 client program. This can be done
SET PASSWORD statement and
SET PASSWORD FOR->
some_host' = OLD_PASSWORD('
UPDATE mysql.user SET Password = OLD_PASSWORD('->
WHERE Host = 'mysql>
some_host' AND User = '
Substitute the password you want to use for
newpwd」 in the
preceding examples. MySQL cannot tell you what the
original password was, so you'll need to pick a new one.
Tell the server to use the older password hashing algorithm:
Start mysqld with the
Assign an old-format password to each account that has had its password updated to the longer 4.1 format. You can identify these accounts with the following query:
SELECT Host, User, Password FROM mysql.user->
WHERE LENGTH(Password) > 16;
For each account record displayed by the query, use
User values and assign a password
SET PASSWORD or
UPDATE, as described earlier.
Note: In older versions of
mysql extension does not support
the authentication protocol in MySQL 4.1.1 and higher. This is
true regardless of the PHP version being used. If you wish to
mysql extension with MySQL 4.1 or
newer, you may need to follow one of the options discussed
above for configuring MySQL to work with old clients. The
mysqli extension (stands for "MySQL,
Improved"; added in PHP 5) is compatible with the improved
password hashing employed in MySQL 4.1 and higher, and no
special configuration of MySQL need be done to use this MySQL
client library. For more information about the
mysqli extension, see
It may also be possible to compile the older
mysql extension against the new MySQL
client library. This is beyond the scope of this Manual;
consult the PHP documentation for more information. You also
be able to obtain assistance with these issues in our
MySQL with PHP
For additional background on password hashing and authentication, see 「MySQL 4.1 のパスワードハッシュ」.