Unable to set smb password

Hi.

Since I got a reboot loop after upgrading to 3.11.9 i decided to try 4.0.1. I followed this guide to create new user for SMB access. however every time I run “smbpasswd -a newuser” I get response: “Failed to open /etc/samba/smbpasswdroot@turris:/etc/samba#”

Any idea how to fix this?

Thanks.