POE no longer uses its own compiler configuration file (/usr/lpp/ppe.poe/lib/poe.cfg is no longer shipped). If you had modified poe.cfg in previous versions, you may need to make similar changes in the default compiler configuration files or to your compiler scripts. The poe.cfg file is saved as part of a migration installation, so any previous changes are preserved. See How Installing the POE Fileset Alters Your System for the files that are saved.