I originally started my server with a given user name and no password.
When I change my password with the setpassword command, it does not appear to work correctly for me.
I've tried logging in with both a blank password and with the new one entered with the command. Invalid password is returned for both attempts.
I've tried restarting the server.
I've gone into the auth.txt file and verified that the password was added and it is correct.
The only way I could log back in was to delete the password from the auth.txt file to return it to a blank value.