It is not gdm issue, you can easily fix it by edit /etc/pam.d/gdm
replace this line: @include common-auth with auth required pam_unix.so nullok
Because common-auth will check if the login user has a tty when empty password is provide. But you can not get a tty from gdm login window.
It is not gdm issue, you can easily fix it by edit /etc/pam.d/gdm
replace this line:
@include common-auth
with
auth required pam_unix.so nullok
Because common-auth will check if the login user has a tty when empty password is provide.
But you can not get a tty from gdm login window.