Office Automation App Fails On Office 365 Machines

Question

I have an application that does COM automation with Excel.  I use Microsoft.Office.Interop.Excel from C#.
The application works fine if Office 2010 is installed.  On machines with Office 365 installed, I get the following error:
System.InvalidCastException: Unable to cast COM object of type 'System.__ComObject' to interface type 'Microsoft.Office.Interop.Excel.Application'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{000208D5-0000-0000-C000-000000000046}'
failed due to the following error: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)).
Code is trivial to reproduce:
using System;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using Excel = Microsoft.Office.Interop.Excel;
namespace TestExcel
    class Program
        static void Main(string[] args)
            // Start Excel and get Application object.
            Excel.Application excelApp = new Excel.Application(); // Fails here
            // Set some properties.
            excelApp.Visible = false;
            excelApp.DisplayAlerts = false;
            excelApp.Quit();
            Marshal.ReleaseComObject(excelApp);
Any ideas how to fix this?
Matt
Matt

Answer 1

Hi Matt.
Which version of COM do you reference?
If you reference version 15.0 in your application, I recommend that you could try this way:
1.Delete the Excel reference (Microsoft.Office.Interop.Excel). Version 15.0.
2.Add the Excel reference (older one. Version 14.0).
Hope that helps.
If your application still causes this error, please let me know.
Thanks.
George Hua
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