Getting NRPE: Unable to read output
Try restarting NRPE on the remote host and see if it goes away!
Reference here: http://dan.langille.org/2010/03/10/nrpe-unable-to-read-output/
For the really tough stains:
Check permissions (does the script require root?), do you need to add nagios to sudoers?
Reference here: http://crashatau.blogspot.com/2007/04/nrpe-unable-to-read-output.html
How about adding in the debug in nrpe.cfg? I.E. debug=1;
Reference here: - just go check the Nagios / NRPE docs!