The error is caused by OS X trying to save metadata for copied files in resource forks (NT terminology) / named streams (Mac terminology). If the server (usually Samba) doesn’t support this it can be disabled

  1. For a Mac user, when connecting to any SMB server, write
    [default] streams=no in ~/Library/Preferences/nsmb.conf
  2. For all Mac users, when connecting to a specific share
    touch "/shared dir/"
    while there, you should also do a
    touch "/shared dir/.metadata_never_index"
  3. Samba can also disable the forks and extended attributes for all clients, use
    [global] ea support = no unix extensions = no in /etc/smb.conf