I'm rolling out version 4.13-2 of Virtualmin virtual-server module to all repos. This is a bugfix release to fix the MySQL/MariaDB backup bug that was introduced in 4.13.
Brief explanation of what happened: 4.13 introduced a number of security fixes, which make Virtualmin perform more actions as the user that owns the account, including backups.There was a side effect to this change that we didn't catch in testing.
Apologies for any inconvenience this may have caused. May all your future backups go off without a glitch (and may you never need them).