Assume that you use the Add this data to the Data Model option to insert PivotTables that contain the Turkish letter "i" into a workbook in Microsoft Excel 2013. Then, you save the workbook as an .xlsx file. When you open the file in Microsoft Excel 2010, you receive the following error message:
Excel found unreadable content in workbook name. Do you want to recover the contents of this workbook? If you trust the source of this workbook, click Yes.
This is a known issue in Excel 2013.