There is no specific preparation you need to do to upgrade to JExcel x.yz. However, if you are upgrading from any version below JExcel a.bc. it's very important that you follow the x.yz. preparation guide.
Upgrading from JExcel SERVER LITE or PRO (server) 1.11.6 to the latest!JExcel NEXT or JExcel DC:
Uninstall all the 3 modules of JExcel:
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