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 higher 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 higher 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.
mysql> SET PASSWORD FOR -> 'some_user'@'some_host' = OLD_PASSWORD('new_password');
Substitute the password you want to use for “
new_password” 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:
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
Uservalues and assign a password using one of the methods described previously.
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
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 higher, 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
mysqli extension, see
For additional background on password hashing and authentication, see Section 126.96.36.199, “Password Hashing in MySQL”.