Dave, only keep the most up to date versions of the jar-files, remove ALL jar-files with older revision numbers.
Update, still trying to solve…..
When I update the ExcelImporter with version 10.1.3 it all goes well, but when I update to the next version 10.2.0 (or 10.3.0 or 10.4.0) it fails and I get the error in this post. I only updated this module.
We’re having the same problem after upgrading from Studio Pro 9.24.2 to 10.1.1. We were already using Excel Importer 10.4.0 and got this error. We re-installed it hoping it would overwrite the existing .jar files but we still get the error. Somewhere in its dependencies (.jar files) it is incorrectly extending a “final” class. See this StackOverflow post:
https://stackoverflow.com/questions/18138136/cannot-inherit-from-final-class-error
We are troubleshooting by trying to find all the .jar files that might conflict. No luck yet.
We solved it! It had nothing to do with dependencies and .jar files. Ignore the information I posted above. The error was caused by a problem with the data in the Excel file we were trying to import using the Excel Importer module and an import template. Presumably the bad data caused the Java code to fail in an unexpected way and generate the error we were seeing.
In our case, the solution was to copy all the data out to a text editor (Notepad++) then copy the data from Notepad++ (Select All and Copy again from Notepad++ so it doesn’t have any “hidden” formatting codes), create a new workbook in Excel, paste the data in and and Save As “Excel 97-2003 Workbook (*.xls)”. That removed extraneous “hidden” formatting codes that we couldn’t see in Excel. The file imported without any errors after doing this.