1959432 - Error: “Excel Found unreadable content in 'File name .xlsx'" while opening the .xlsx file generated from Web Intelligence document

 When a Web Intelligence report is saved in Excel format, the generated excel file fails to open with the following error-
"Error: “Excel Found unreadable content in 'File name .xlsx'. Do you want to recover the content of this workbook? If you trust the source of this workbook, click Yes” when open the Excel file generated from Webi."

If click on ‘Yes’ for the above message then following error is seen:
“Excel cannot open the file ‘filename.xlsx’ because file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file”