In the "#======================= Share Definitions =======================" section of smb.conf exists the original [homes] share from Debian which looks like this but is scattered throughout the section:
[homes]
comment = Home Directories
browseable = no
read only = yes
create mask = 0700
directory mask = 0700
valid users = %S
Ubuntu usually comments out this share but in this case it was incomplete. Only [homes], "comment = Home Directories", and "browseable = no" were commented out.
This leaves "read only = yes", "create mask = 0700", "directory mask = 0700" and "valid users = %S" intact and interpreted by samba as global parameters which makes a mess of things. In this particular bug report having "valid users = %S" interpreted as a global parameter induces the originally posted error message.
All of the [homes] share parameters must be commented out.
In the "#===== ======= ======= ==== Share Definitions ======= ======= ======= ==" section of smb.conf exists the original [homes] share from Debian which looks like this but is scattered throughout the section:
[homes]
comment = Home Directories
browseable = no
read only = yes
create mask = 0700
directory mask = 0700
valid users = %S
Ubuntu usually comments out this share but in this case it was incomplete. Only [homes], "comment = Home Directories", and "browseable = no" were commented out.
This leaves "read only = yes", "create mask = 0700", "directory mask = 0700" and "valid users = %S" intact and interpreted by samba as global parameters which makes a mess of things. In this particular bug report having "valid users = %S" interpreted as a global parameter induces the originally posted error message.
All of the [homes] share parameters must be commented out.