There are many different types of errors that may be reported by yod when a user attempts to load an application. Some of the errors are detected by yod, for example when an executable was compiled with the wrong version of the Cplant libraries. Some of the errors are reported to yod by the PCTs, such as a compute node failure during the load.
Often when there is a problem in the compute partition, the first symptom of the problem is that an application fails to load. yod will attempt to display the compute node or nodes that is failing in the load. You can configure yod to send mail to system administrators when a compute node failure is detected. In the site file (see chapter 11) define the NOTIFY_LIST to be the list of their email addresses, and be sure to enable mail on the service node.
Some load errors are listed in the user log file written by yod when it terminates, and also logged to /var/log/cplant. You can check these two files when investigating problems.