I found out what the problem is:
Turn off PHP safemode in php.ini. Change the value safemode=on to off and restart your apache. (This made it work for me)
It’s because the owner of the Backup-Files will be (in my case) www-data:www-data. And if safemode is on, user www-data has no permission to write into the backup-db directory while it is owned by root or other user.
Best Regards
PS: Reply please if its working for you or not.
