Session declined. Maximum number of open sessions reached

Systems utilizing gdm (or gdm-binary) through an XDMCP daemon may see a message which states that the session was declined because the maximum number of open sessions was reached.

This means that gdm is currently putting a limit on the number of XDMCP sessions. The default limit is set to 16 connections and as such the total number of XDMCP sessions that are able to connect to the machine is 16.

To change the default limit, please use the following instructions:

1. Edit the /etc/gdm/custom.conf or gdm.conf file.

   [xdmcp]
   ...
   MaxSessions=99 (<= gdm does not support over 99 XDMCP sessions.)

2. Restart the top-level process within the gdm(or gdm-binary) processes.

   #ps -aef grep dm grep -v grep
   root 20483 1 0 16:01 ? 00:00:00 /usr/sbin/gdm-binary -nodaemon
   root 24855 20483 0 23:04 ? 00:00:00 /usr/sbin/gdm-binary -nodaemon

   # kill -1 20483