Resolution:
During upgrade from GridServer 4.2 to GridServer 5.x, Engine configurations are copied to the updated grid but not checked for incompatibility with the upgrade. For example, gcc2 for Linux is no longer supported. However, during upgrade, this value is maintained for any Engine specifying gcc2 as the value for Engine GCC built version before the upgrade. You must change this Engine configuration setting yourself; go to Engine > Engine Configuration in the Classes, Libraries, and Paths section.