A.2.3. Client does not support authentication protocol
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 4.1,
attempts to connect to it 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 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 using the
SET PASSWORD statement and the
OLD_PASSWORD() function:
mysql> SET PASSWORD FOR
-> 'some_user'@'some_host' = OLD_PASSWORD('newpwd');
Alternatively, use UPDATE and
FLUSH PRIVILEGES:
mysql> UPDATE mysql.user SET Password = OLD_PASSWORD('newpwd')
-> WHERE Host = 'some_host' AND User = 'some_user';
mysql> FLUSH PRIVILEGES;
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
--old-passwords option.
-
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 the
OLD_PASSWORD() function and either
SET PASSWORD or
UPDATE, as described earlier.
Note: In older versions of PHP,
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
https://php.net/mysqli.
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
forum.
For additional background on password hashing and
authentication, see Section 5.7.9, “Password Hashing as of MySQL 4.1”.
