# Frequently asked questions

## Q: Will *Percona Server for MySQL* with *XtraDB* invalidate our *MySQL* support?

A: We don’t know the details of your support contract. You should check with
your *Oracle* representative. We have heard anecdotal stories from *MySQL*
Support team members that they have customers who use *Percona Server for MySQL* with
*XtraDB*, but you should not base your decision on that.

## Q: Will we have to *GPL* our whole application if we use *Percona Server for MySQL* with *XtraDB*?

A: This is a common misconception about the *GPL*. We suggest reading the *Free
Software Foundation* ‘s excellent reference material on the [GPL Version 2](https://www.gnu.org/licenses/old-licenses/gpl-2.0.html), which is the license
that applies to *MySQL* and therefore to *Percona Server for MySQL* with *XtraDB*. That
document contains links to many other documents which should answer your
questions. *Percona* is unable to give legal advice about the *GPL*.

## Q: Do I need to install *Percona* client libraries?

A: No, you don’t need to change anything on the clients. *Percona Server for MySQL* is
100% compatible with all existing client libraries and connectors.

## Q: When using the *Percona XtraBackup* to set up a replication replica on Debian-based systems I’m getting: “ERROR 1045 (28000): Access denied for user [‘debian-sys-maint’@’localhost](mailto:'debian-sys-maint'@'localhost)’ (using password: YES)”

A: In case you’re using the init script on Debian-based system to start `mysqld`,
be sure that the password for `debian-sys-maint` user has been updated and
it’s the same as that user’s password from the server that the backup has been
taken from. The password can be seen and updated in
`/etc/mysql/debian.cnf`. For more information on how to set up a
replication replica using *Percona XtraBackup* see [this how-to](https://docs.percona.com/percona-xtrabackup/8.0/set-up-replication.html).