Try to open my Excel file using C# and get an error

Question

I try to read my Exel file from code and received System.InvalidCastException:

Additional information: Unable to cast COM object of type \'System.__Co

Answer 1

Workbook.ActiveSheet Property might not be the best choice for programmatically opened Excel files as it can actually return a non-Worksheet object

You might want to consider checking sheets count and using indexes:

int count = newWorkbook.Worksheets.Count;
if (count > 0)
{
    objsheet = (Worksheet) newWorkbook.Worksheets[1];
}

And try not to break the 2-dot rule - you'll need to release all you COM's to properly close your app and Excel.

Edited:

You could be mixing Microsoft.Office.Interop.Excel with Microsoft.Office.Tools.Excel namespaces.

Try to declare and assign as follows:

private static Microsoft.Office.Interop.Excel.Worksheet objsheet = null;
...
objsheet = (Microsoft.Office.Interop.Excel.Worksheet) newWorkbook.Worksheets[1];