Re: NoClassDefFoundError: while reading XLSX file using XSSF cls for getCellType() /getStringCellVal
Just one last thought, I've just checked the "lib" folder of my Ready API installation. it actually contains the poi-* jar files. It looks like Ready API is installed with it's own copy of the Apache POI library, version 3.12 (Note: I'm currently running version 1.7).
Perhaps there is some sort of clash between the pre-installed version 3.12 and the additional 4.0.1 you have added to the ext directory. I note that the pre-installed version does not have the full ooxml-schemas file in the lib directory, possibly your code may be using this version?
A couple of suggestions:
Perhaps try just deleting the version you have added to the ext directory and use the pre-installed libraries?
Perhaps add just the file ooxml-schemas-1.3.jar to the lib (or ext) directory.