/etc/gdm/PreSession/Default: Registering your session with wtmp and utmp
/etc/gdm/PreSession/Default: running: /usr/X11R6/bin/sessreg -a -w /var/log/wtmp -u /var/run/utmp -x "/var/lib/gdm/:0.Xservers" -h "" -l ":0" "conn"
/etc/gdm/Xsession: Beginning session setup...
The program 'x-session-manager' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadImplementation (server does not implement operation)'.
  (Details: serial 84 error_code 17 request_code 154 minor_code 5)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)