In one of my project, I am using OpenXML SDK for opening Excel files. Recently I got an issue like SpreadsheetDocument.Open() method was throwing an IOException, if the Excel file is opened by MS Excel, even if I set the isEditable parameter false.

I fixed this problem by passing a stream instead of string (file path). And I used the File stream class to open the Excel file. Here is the code snippet.

using (var fileStream = new FileStream(fileName, FileMode.Open, 
    FileAccess.Read, FileShare.ReadWrite))
{
    using (var spreadSheetDocument = SpreadsheetDocument.Open(fileStream, false))
    {
        //Implementation
    }
}

Happy Coding :)