unable to cast COM object of type 'microsoft.Office.Interop.Excel.ApplicationClass' to 'microsoft.Office.Interop.Excel.Application'\"

Question

This is my first attempt to capture some data from excel from within one C# console application.

I get the error "unable to cast COM object of type 'microsoft.Office.Interop.Excel.ApplicationClass' to 'microsoft.Office.Interop.Excel.Application'".

This code used the 'Microsoft Excel 12.0 Object Library' , and I gave reference to Microsoft.Office.Interop.Excel.

Still, I could not get over this error - which I believe has its own quick solution.

I digged a little bit this site and came across with this solution: Interop type cannot be embedded

However, I could not understand so could not implement what was suggested as a solution.

My .Net version is 4.5.

Any help is very much appreciated.

Thanks in advance.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;

using Excel = Microsoft.Office.Interop.Excel;

namespace deneme
{
class Program
{
    static void Main(string[] args)
    {

        Excel.Application xlApp = new Excel.Application();
        xlApp.Visible = true; // <-- excel application
        xlApp.DisplayAlerts = false;

        // Open the workbook.
        Excel.Workbook wBook = xlApp.Workbooks.Open("C:\\FNN\\XLA\\fnnComTemplate.xlsx",
            Type.Missing, Type.Missing, Type.Missing, Type.Missing,
            Type.Missing, Type.Missing, Type.Missing, Type.Missing,
            Type.Missing, Type.Missing, Type.Missing, Type.Missing,
            Type.Missing, Type.Missing);

        // get the sheet
        Excel.Worksheet wSheet = wBook.Sheets[0];
        // foreach (Excel.Worksheet sheet in wBook.Sheets) { if (sheet.Name == "templateSheet") { wSheet = sheet; } }

        Excel.Range rng = wSheet.get_Range("A1");

        aux = wSheet.Range["F6"].Value;

        Console.WriteLine("interop result:" + aux);
        Console.ReadLine();

    }

}
}

Answer 1

If this is not a code related error than please remove below given key from registry.

Steps:

Start--> Run --> regedit --> HKEY_CLASSES_ROOT-->TypeLib-->{00020813-0000-0000-C000-000000000046} --> 1.8/1.7 (Delete this)

Solution: This issue can be resolved by deleting an invalid registry key left over from the higher version of Office. Follow the above steps.

Cause: This issue is caused by a left over registry key if you have downgraded your version of Microsoft Office from either Office 2010 to Office 2007, or Office 2013 to Office 2010 or 2007.

Let me know if this solution is not helped to you

Answer 2

Microsoft Office 365

I was running Microsoft Office 365 with Windows 10 and tried the mentioned solutions to remove the registry key without success.

I went to the control panel in an attempt to repair the Office 365 suite.

I selected the quick repair

Tried my program again and everything worked!

Answer 3

I am sure the answers to this question (and similar questions) proposing editing the registry and removing old references to versions of Office no longer on the machine are correct.

I am only adding this answer because I am currently kicking myself. Two hours spent hunting keys in the registry and getting nowhere. Last throw of the dice was to try a simple repair on Microsoft Office and suddenly my error is gone.

... seems to me it's worth trying a repair before getting too deep into manually editing the registry.

Answer 4

A machine had been updated to Office 2016 64-bit and the COM interface was throwing exceptions when called from the a 32-bit application. It did not have old TypeLib entries like the ones in Jayesh's answer.

Comparing ProcessMonitor traces to a working machine with Office 2016 led to what look like dead end registry keys in

HKEY_CLASSES_ROOT\Wow6432Node\TypeLib\{00024..

The working machine would check for the non-existent registry key and return

NAME NOT FOUND

The failing machine had the registry key but then would throw an exception shortly thereafter.

After repeatedly deleting the registry key, rerunning the trace, deleting the next failing key, the COM interface functionality was restored.