With a Joomla 3.4.8 and CiviCRM 4.6.14 setup, I have been unable to run a simple cronjob. Upon suggestion from my host support team I generated a new site-key [following instructions on https://wiki.civicrm.org/confluence/display/CRMDOC/Managing+Scheduled+Jobs]. I replaced the old key with the new one in both civicrm.settings.php files and ran the following cronjob on Terminal - curl -s http://ashguild.ca/home/administrator/components/com_civicrm/civicrm/bin/cron.php?name=username&pass=password&key=key but I am still getting the same error message. Any help would be appreciated.
Check that the user in your cron-script has superuser access in Joomla.
I encountered this with a password (or key) that had special characters. Don't use special characters for the password/key you want to use. Keep it [a-z] [A-Z] [0-9] (alphanumeric).