I found what I think is a weird behaviour when trying to create a backup of a database using the feature Edit Databases > Manage Database > Backup Database. If the backup is created at that moment (using the Backup Now button) the backup gets indeed created, but the .sql file ends with the lines
-- Dump completed on 2016-12-15 23:47:16 Scheduled backup for database left disabled.
The backup is completely valid and will work when it gets imported - but any manager, Virtualmin included, complains about that last incomplete HTML line throwing a syntax error (even though the sql content is already imported correctly).
I tried in two different Virtualmin installations - in different servers, both of them updated to the last version.