You just bought a nice piece of web software, uploaded it to your site, did some advertising, got some good users, and every thing looks so nice and rosy.

And one fine day, you decide to do upgrade your Mysql and oops, your web application stops working and reports this error.

Warning: mysql_pconnect() [function.mysql-pconnect]: Client does not support authentication protocol requested by server; consider upgrading MySQL client.

I know. It is really irritating to see errors like this. But this is a very simple issue and can be corrected easily. This happens because, Mysql 5 suddenly decided to use a different password hashing algorithm that is incompatible with older clients.

So, what is the remedy? You can choose any one of the following options.

1) Upgrade all your client programs.
2) If you have a mysql account which still has older type password, use that account.
3) Try out this simple command.

SET PASSWORD FOR ‘some_user’@’some_host’ = OLD_PASSWORD(‘newpwd’);

4) Start mysqld with the –old-passwords option.

More details are available here.