If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.

If you receive Microsoft Excel cannot access the file, There are several possible reasons error message you can use the following suggestions to resolve the issue.

We need to import data from Excel file from our client. Recently we migrated to ClosedXML from EPPlus due to the change of license. The migration progress is quite smoothly until the acceptance test ...