The current implementation of the authentication protocol uses a password hashing algorithm that is incompatible with that used by older (pre-4.1) clients. Attempts to connect to a 4.1 or newer server with an older client may fail with the following message:
shell> mysql
Client does not support authentication protocol requested
by server; consider upgrading MySQL client
To deal with this problem, the preferred solution is to upgrade all client programs to use a 4.1.1 or newer client library. If that is not possible, use one of the following approaches:
To connect 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
using the SET PASSWORD
statement and the
OLD_PASSWORD() function:
mysql>SET PASSWORD FOR->'some_user'@'some_host' = OLD_PASSWORD('newpwd');
Substitute the password you want to use for
“newpwd” in the
preceding example. 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 by default:
Start mysqld with the
old_passwords system
variable set to 1.
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:
mysql>SELECT Host, User, Password FROM mysql.user->WHERE LENGTH(Password) > 16;
For each account record displayed by the query, use
the Host and
User values and assign a password
using one of the methods described previously.
The Client does not support authentication
protocol error also can occur if multiple versions
of MySQL are installed but client programs are dynamically
linked and link to an older library. Make sure that clients
use the most recent library version with which they are
compatible. The procedure to do this will depend on your
system.
The 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 use the 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
http://php.net/mysqli.
For additional background on password hashing and authentication, see Section 6.1.2.4, “Password Hashing in MySQL”.