com 异常 excel InteropServices.COMException - c#

Question

I am receiving System.Runtime.InteropServices.COMException when running the below method from main()

I want to get true and later access the sheet if excel is opened on system. I am making sure excel is opened and sheet1 is there but I get false and the error above.

using Excel = Microsoft.Office.Interop.Excel;

         public static bool IsExcelOpened(string sheet1)
    {
        bool isOpened = true;
        Excel.Application exApp;
        exApp = (Excel.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");
        try
        {
            Excel.Worksheet xlWorksheet;
            xlWorksheet = (Excel.Worksheet)exApp.Workbooks.get_Item(sheet1);
        }
        catch (Exception)
        {
            isOpened = false;
        }
        return isOpened;
    }

EDIT: when I run VS2019 as admin, I received more infor on error

Operation unavailable (Exception from HRESULT: 0x800401E3 (MK_E_UNAVAILABLE))

Answer 1

I think your issue is Visual Studio running in a different context to Excel.

I tried a slightly modified version of your code and it works just fine when running Visual Studio NOT as admin (same user as excel was opened with).

Might be worth checking you are using the right version of the interop dll also.

public bool IsExcelOpened()
        {
            bool isOpened = false;

            try
            {
                Excel.Application exApp;
                Excel.Worksheet xlWorksheet;
                exApp = System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application") as Excel.Application;
                if(exApp != null)
                {
                    xlWorksheet = (Excel.Worksheet)exApp.ActiveSheet;
                    isOpened = true;
                }
            }
            catch { }
            return isOpened;
        }

Answer 2

I also was facing the same issue, the main reason is Microsoft doesn't support the Automation of Microsoft Office applications from any unattended, non-interactive client application or component (including ASP, ASP.NET, DCOM, and NT Services). So, I tried to manually register the excel to ROT (running object table) by using a shell command like Process.Start("Path to your excel file") before creating the Marshal.GetActiveObject() .