Generally speaking when we see the message "Unable to spool message"
There are one of three reasons
1- We can not write out to the local file system or the disk is full.
2- There is something blocking the port we are trying to communicate on such as a firewall. Firewalls should be disabled or allow port 48000-48050.
(you would also need to set first_probe_port = 48000 in the robot.cfg)
3- The robot is temporarily busy.
Sometimes, it is required to exclude the Nimsoft folder from your antivirus software.