I posted this on the recent failed backup thread over here: http://virtualmin.com/node/35764#comment-142515
I have upgraded to the latest 4.13-2 release and yet my MySQL backups are failing.
The error is
Dumping MySQL database db_prod1 .. .. dump failed! mysqldump: Got error: 1045: Access denied for user 'root'@'localhost' (using password: YES) when trying to connect
It was suggested I check to make sure the MySQL root password was the same, and I reset it then changed it in MySQL Module config. I ran a backup and the error still persists.