Having problems backing up your virtual hosts with virtualmin after the upgraded to 4.13 (available around january the seventh 2015)?
The source of the problem is that mysqldumps are now executed under the domain account (for security reasons). As is obvious this does not always work correct. For this moment there is a quick fix thanks to the great support folks at virtualmin.com.
Check here for the quickfix (the restart of the virtualmin server is mandatory :-)).