Ubuntu – How to enable user sharing per instructions

The directory /var/lib/samba/usershares is set up so only root or members of the sambashare group can read or write to it.

drwxrwx--T  2 root sambashare  4096 Mar 25  2012 usershares

That you can't access it (try it by cding to it) suggests to me that you're not in the sambashare group. You can test this with id $USER and assuming usershares is not in the output, you can fix all this just by running:

sudo usermod -a -G sambashare $USER

If you still get error 255 after adding the particular user to the group you might need to reboot.

Nautilus uses the net usershare info command to get information about non-root user defined Samba shares. See the net manpage for more about this command.

If that command fails Nautilus assumes there are no such shares and displays the error message it got just in case you want it.

Creating the folder /var/lib/samba/usershares/ should prevent the message from appearing:

sudo mkdir -p /var/lib/samba/usershares/