I see the following dependencies:
You say you updated the excel importer and exporter, but are the other ones also updated?
I mangaed to solve it after trawling around stackoverflow for similar problems.
The problem was some conflicting .jars presumably imported by updating the Excel Exporter module. I simply removed all references to poi-ooxml-4.1.2.ja in the userlib and the runtime automatically used v5.
Here is a reference to the stackoverflow post:
apache poi - Exception in thread "main" java.lang.NoSuchFieldError: Factory - Stack Overflow