Parsing a file using FlatFileSchema and pubflatFileconvertToValues

To be Frank i am not sure about this problem.
But try this option once you are done with getFile and loadAS:bytes then convert output body/bytes to String (bytesToString) and map this to convertToValues (ffData).See the error disappears.

And this might be a validation issue basing on this post,same error but its EDI document.

If i found any clue i will post it.