I figured it out myself. Problem is:
In interface settings, I have database prefix set to "db_". Database backup script then preppend ANOTHER "db_" prefix to backup name, so result is db_db_name.tar.gz. This 2x "_" then confuse the restore script, because it uses for resolve database name this:
$parts = explode('_',$backup['filename']);
$db_name = $parts;
so in variable $db_name is "db" and script will fail. Same problem will happen when database name contains "_" .
Last edited by cassus; 4th March 2013 at 22:25.