can't add usershares using nautilus-share

When I try to add usersahre using nautilus-share pulgin I get the following error 'net usershare' returned error 255: net usershare add: cannot convert name "Everyone" to a SID. The transport connection is now disconnected.. my smbd.conf content :

[global]
   workgroup = WORKGROUP
   dns proxy = no
   log file = /var/log/samba/%m.log
   max log size = 1000
   server min protocol = SMB2_02
   server max protocol = SMB3
   server role = standalone server
   passdb backend = tdbsam
   obey pam restrictions = yes
   unix password sync = yes
   passwd program = /usr/bin/passwd %u
   passwd chat = *New*UNIX*password* %n\n *ReType*new*UNIX*password* %n\n *passwd:*all*authentication*tokens*updated*successfully*
   pam password change = yes
   map to guest = Bad Password
   usershare allow guests = yes
   name resolve order = lmhosts bcast host wins
   security = user
   guest account = guest
   guest ok = yes
   usershare path = /var/lib/samba/usershares
   usershare max shares = 100
   usershare owner only = false
   force create mode = 0070
   force directory mode = 0070
   load printers = no
   printing = bsd
   printcap name = /dev/null
   disable spoolss = yes
   show add printer wizard = no

[homes]
   comment = Home Directories
   browseable = no
   read only = yes
   create mask = 0700
   directory mask = 0700
   valid users = %S

[printers]
   comment = All Printers
   browseable = no
   path = /var/spool/samba
   printable = yes
   guest ok = no
   read only = yes
   create mask = 0700

[print$]
   comment = Printer Drivers
   path = /var/lib/samba/printers
   browseable = yes
   read only = yes
   guest ok = no

also i checked that my user is in sambashare group and the directory /var/lib/samba/usershares has the following attributes drwxrwxrwx 2 root sambashare 4096 فبر 5 19:11 usershares

any suggestion with this issue?

guest account = guest

Do you actually have a user named "guest"? If you do not you will get that exact error message.

Just delete the line in smb.conf ( Samba will default to the user "nobody" ).

Then restart smbd:

sudo service smbd restart

Then try to create the share again.