No definition found for GetActiveObject from System.Runtime.InteropServices.Marshal C#

Question

I'm trying to connect to a running Excel instance, but when I try to use the following code snippet:

using Microsoft.Office.Interop.Excel;
using System.Runtime.InteropServices;

public Application StartExcel()
{
    Application instance = null;
    try
    {
        instance = (Application)Marshal.GetActiveObject("Excel.Application");
    }
    catch (COMException ex)
    {
        instance = new ApplicationClass();
    }

    return instance;
}

I found similar snippets on the internet, but when I compile this code I get the following error:

error CS0117: 'Marshal' does not contain a definition for 'GetActiveObject'.

I do not know why, because I have the following NuGet packages: - Microsoft.Office.Interop.Excel - System.Runtime.InteropServices

Answer 1

This is available only .Net Framework but not for .Net Core . Please check the .Net project type .

https://learn.microsoft.com/en-us/dotnet/api/system.runtime.interopservices.marshal.getactiveobject?view=netframework-4.8&viewFallbackFrom=netcore-2.2