问题 I have an error while trying to read excel files ( xlsx ) which were saved in Excel 2007 using EPPlus library. Some workaround: ASP.net mvc 5 app with EPPlus v. 4.0.4.0 User can download template file from my site, then fill required data in it, and upload it back. File contains 4 worksheets, one of them is hidden . Workbook is password protected, worksheets are proteced too. All of them have different passwords. Template file ( xlsx ) produced in Excel 2007 or 2010 . When user posts file