When upgrading ZMF it can sometimes be easy to overlook the migration step that covers the re-build of the assembler exits (i.e. those named CMNEXnnn). However, significant changes to the shipped CMNEXITS copybook in the ZMF 8.3 release make this extremely important when migrating to ZMF 8.3 or, in future, when migrating to any release that spans the original ZMF 8.3 GA release. Failure to rebuild these exits could result in a number of different failures that could potentially span almost every facet of ZMF processing.

A knowledgebase article that echoes this message and which contains an example of such a failure can be found here.