[Reprint] MYSQL upgrade due to "Client does not support authentication protocol requested by server" ...

Client does not support authentication protocol requested by server;
all users to install Mysql4.1 or later see this article !!!!!!!!!

Mysql 4.1 and above to use the new cryptographic algorithms, and PHP does not support the new algorithm, so after new users, need to use the following method to solve the problem of Mysql PHP can not connect Login: (which some_user, some_host, newpwd are the user name of your database, host, password)

[b] A first solution: [/ B]
MySQL> the FOR PASSWORD the SET
    -> 'some_user' @ 'some_host' = the OLD_PASSWORD ( 'newpwd');

Let's say the database user is admin, the host localhost, password is 123456

This command should be entered when:

MySQL> the SET PASSWORD the FOR ADMIN = @ localhost the OLD_PASSWORD ( '123456' );
[Thanks to this example do henrykim]

The second solution:

mysql> UPDATE mysql.user SET Password = OLD_PASSWORD('newpwd')
    -> WHERE Host = 'some_host' AND User = 'some_user';
mysql> FLUSH PRIVILEGES;

A third solution (not recommended)

Mysqld option is enabled by --old-passwords, and then change the existing user using the above method

Taken Mysql official website: http://dev.mysql.com/doc/mysql/en/old-client.html

Reproduced in: https: //www.cnblogs.com/leaway/archive/2006/08/24/485706.html