The error message
Error No. 1045: Connection denied for 'someuser@somehost' (using password: YES/NO)
is a user authentication error. The user details specified do not "match" the user tables of the specified MySQL server. Common situations are
* No such user.
NOTE: MySQL does not use the OS's or domain's user's management. It operates its own user accounts. With a fresh MySQL installation the user ROOT is created with NO PASSWORD. When working with MySQL databases at ISP's an admin user most often must be activated from some web based Control Panel Application before connection to the MySQL server is possible. There could be more "rules" applying here (database and user naming conventions etc). Refer to the docs/support at the ISP for details on that. We can't give them!
* User is not allowed to connect from the actual host. Note that MySQL by default only allows connection from 'localhost'. To specify from where a user may connect SQL wildcards (% and _) can be used. Simply 'someuser@%' means that user 'someuser' may connect from everywhere.
* Wrong password, missing password or password specified where it should not
* If you are upgrading MySQL from an old version (4.0.x or lower) to a more recent (4.1.x or highere) and if you are still using a rather old PHP version you may need to execute this command from command-line client
SET PASSWORD FOR some_user@localhost = OLD_PASSWORD('newpwd');(where some_user@localhost is the user used for this connection) since the format for storing passwords has changed between 4.0.x and 4.1.x versions.