Closing an Excel Workbook

Question

I have a bit of code that opens an xls workbook;

Excel.Workbooks workBooks;
workBooks = excelApp.Workbooks;
workbook = workBooks.Open(sourceFilePath + source         


        

Answer 1

This question keeps popping up see:

How to properly clean up Excel interop objects in C#

You need to call System.Runtime.InteropServices.Marshal.ReleaseComObject() on every excel object you use, even invisible ones, e.g.:

var worksheet = excelApp.Worksheets.Open()

There are two objects here: 1. The obvious 'Worksheet' opened with Open() 2. The "invisible" collection 'Worksheets'.

Both of them need to be released (so you better keep a reference for Worksheets):

var wkCol = excelApp.Worksheets;
var worksheet = wkCol.Open();