Did you find solution to this problem? I am facing same problem. My Ubuntu is
9.04. Maxima is by default 5.13.0 installed through aptitude. I am using Apache2 , MySql and Moodle 1.9.9
I installed STACK and configured with Maxima and Moodle. On running TestSuite
at the end of STACK istallation it shows connection error with Maxima using
command "maxima". Otherwise I am able to start Maxima.
Did you upgrade Maxima version from 5.13.0 or your Ubuntu version?