Thanks for the template file, sample code and error stack trace.
I noticed the exception “java.lang.ArrayIndexOutOfBoundsException” when loading the file via Aspose.Cells APIs. But when I tried to open the file into MS Excel manually, I also found an error message, see the screenshot for your reference:
And, MS Excel has to attempt to recover the file and I doubt the final file is not even fully recovered (in MS Excel) as it gives error messages regarding PivotTable(s). In short, your template file is corrupt and MS Excel itself cannot open it directly. I am afraid, if an Excel file is corrupted, Aspose.Cells cannot load the file into its object model fine. Please provide a valid file which can be opened fine into MS Excel manually,and which cannot be opened by Aspose.Cells, we will check it soon.
Regarding your issue for Aspose.Slides API, we will check and get back to you soon.