Hi,
g-r-d's built in RDP server does not work
I got the same error message when I used the wrong password by accident. When I started using the correct password I was able to use RDP again. This is with vanilla Debian 12 and gnome.
I would try with an alphanumeric password and verify that it matches the output of
secret-tool lookup xdg:schema org.gnome.RemoteDesktop.RdpCredentials -Timo
