Mysql upgrade and possible problems - please read
As we have announced few months before we will upgrade all our shared hosting cPanel server's Mysql database version to the 5.1.x one.
Until now Mysql had no restrictions in the length of the dbase username, looks like this was a bug and the MySQL developers corrected the bug starting from MySQL 5.1.x, limiting the dbase username length to 16 characters including the required cPanel username and underscore preceding the database name.
To avoid your MySQL dbase based scripts stop working after the mysql upgrade we have to correct this problem.
If you have any MySQL database username longer than 16 characters please proceed to change them.
For example if you have a Wordpress installed you can proceed as instructed below:
1- Login to your cPanel and go to the MySQL databases section.
2- Look at the usernames of any databases, if you see any longer than 16 characters, please create a new database username with 16 or less characters in total (keep in mind the cpanel username and the underscore must be included in the 16 characters total).
3- Give the permissions to the new username to the corresponding database.
4- Go into your WordPress installation's wp-config.php file and update the file to reflect the new MySQL username.
Most scripts have corresponding configuration files and the process to update the database usernames is very similar (for example, Joomla's is called configuration.php). Once the username is updated with the new value, you must be sure you will have no problem once we upgrade the MySQL version.
If you are unsure of how to do this, please do not hesitate to open a support ticket.