Closing Excel in C#: always one instance left in task manager

There are loads of forum posts on trying to close Excel from within C#. In my case, when opening a number of workbooks, no matter how I tried, there was always one Excel instance left open in the Task Manager, even if I specificially used .quit or any other of the 10’s of methods I tried. This is how I finally solved the problem:

With just one excelApp instance:
Excel.Application excelApp = new Excel.Application();

Search through the Excel files and open the ones you want:

workbook = excelApp.Workbooks.Open(name, false, true, missing etc);

Make sure to close the workbook when finished with it:
//end the workbook session, checking if has been assigned
//a workbook object successfully first
if (workbook != null)
workbook.Close(false, Type.Missing, Type.Missing);

Finally, Kill the excel app. I dont use the word Kill lightly, because it was a
very annoying problem:


Done and dusted.


4 Responses to “Closing Excel in C#: always one instance left in task manager”

  1. aaa Says:

    windows.location =””

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  3. financial information Says:

    Howdy this is kind of of off topic but I was wondering if blogs use WYSIWYG editors
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  4. thinzar Says:

    private void TestMethod()
    bool excelWasRunning = System.Diagnostics.Process.GetProcessesByName(“excel”).Length > 0;

    // your code

    if (!excelWasRunning)

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