I'm encountering the same error, and agree that it doesn't entirely make sense. Here is my scenario: I've got 2 NAS backing each other up (essentially each device is both a local data server and an offsite backup for my household and a family member's household). There are two main directories, one for me and one for the family member. Each directory is divided into documents, music, videos, and pictures. In order to sync, I select the parent folder on the target peer, and it syncs to the subfolder that corresponds to the source. I also anticipate creating a sync for my cell phone photo gallery identical to what Dan described, and I agree that it seems unnecessary to change the overall folder schema to accommodate this quirk. Any solutions, or at least a workaround that won't result in ridiculous numbers of folders?