Describes the cause and action for error messages.
Error Message(English)：
2013 cannot open old files
open earlier versions of Excel workbooks in excel 2013 - Super User
https://superuser.com/questions/868913/open-earlier-versions-of-excel-workbooks-in-excel-2013
How can I open .xls file with Excel 2016?
https://superuser.com/questions/1251051/how-can-i-open-xls-file-with-excel-2016
windows 10 - Will Office 365 Home or Personal ...
https://superuser.com/questions/1187542/will-office-365-home-or-personal-open-old-doc-dot-and-xls-fi・・・
You can open old Office files with these settings | PCWorld
https://www.pcworld.com/article/3016278/print-preview-and-open-old-office-files.html
How to Open an XLS File in Excel | Chron.com
https://smallbusiness.chron.com/open-xls-file-excel-64136.html
How to open a 97-2003 Excel file in Office 2013 Excel - Quora
https://www.quora.com/How-do-I-open-a-97-2003-Excel-file-in-Office-2013-Excel
[FIXED] Excel Cannot Open the File Because The Extension Is Not ...
https://www.easeus.com/file-recovery/excel-cannot-open-the-file.html
Repairing a corrupted workbook - Excel - Microsoft Office Support
https://support.office.com/en-ie/article/repairing-a-corrupted-workbook-7abfc44d-e9bf-4896-8899-bd10・・・
How to fix "This file is corrupt and cannot be opened" error in Excel 2013
https://www.youtube.com/watch?v=0XmPQ6NQ3SQ