Error retrieving current backup directories from backend

I’m trying to run backup on an instance of ubuntu server 20.04. When ever I try and set the backup directory with the command:

add-backupdir -x -f -d /dev/xvda2

I get the error:

Error retrieving current backup directories from backend

What am I doing wrong?

/dev/xvda2 is a device, you can’t backup the disk as an image for linux, you must backup the mount point (the files).