This just started happening during the nightly full backup:
mysqldump: Got error: 1045: Access denied for user 'xxxxxx'@'localhost' (using password: YES) when trying to connect
(username was omitted, of course ;-)
The username that it is trying to log in as is not root! Where is the username the backup uses stored?
The only thing I can think of that has changed is the upgrade of webmin and usermin. This may or may not be related. The backups were running fine, to the best of my knowledge. The last backups of the sites that have databases seem to coincide with the upgrade, but it took me a couple of days to notice tht not all of the backups were running correctly.