Crontab error

I have a daily crontab job running on my user documents directory:

rsync -avz /mnt/user/users /mnt/user/Users_Yesterday

This makes sure that there is a continuous copy of all my user documents, the rsync command is set up so it does not replicate deletions ( in other words: If I delete a file in my main documents directory it will always remain on my Yesterday share.. The Yesterday share is a disabled share so I cannot be working on it by accident..

Really nice solutions that costs allmost no space (documents are small)..

I have also made sure that the Yesterday share uses another physical disk then my regular share.. Adding another layer of protection..

After upgrading to the latest release of unraid and simplefeatures I have solved the issue that this crontab job did not run (actually also the mover script did not work, all is fixed now).

My question is pertaining an error message I get out of cron that I do not understand, can someone make sense of the following:

rsync: mknod "/mnt/user/Users_Yesterday/users/marc/command_socket" failed: Function not implemented (38)

rsync: mknod "/mnt/user/Users_Yesterday/users/marc/iface_socket" failed: Function not implemented (38)

rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1042) [sender=3.0.7]

Thanks in advance !