Office application does not quit after automation from Visual Studio .NET client

• Declare each object as a new variable. For example, change the following line of code

  oBook = oExcel.Workbooks.Add()
  					

  to the following:

  dim oBooks as Excel.Workbooks
  oBooks = oExcel.Workbooks
  oBook = oBooks.Add()
  					

• Use System.Runtime.InteropServices.Marshal.ReleaseComObject when you have finished using an object. This decrements the reference count of the RCW.
• To release the reference to the variable, set the variable equal to Nothing or Null.
• Use the Quit method of the Office application object to tell the server to shut down.

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Steps to reproduce the behavior

1. Start Visual Studio .NET.
2. On the File menu, click New and then click Project. Under Visual Basic Projects, select Windows Application and click OK. Form1 is created by default.
3. Add a reference to the Microsoft Excel Object Library. To do this, follow these steps:
   1. On the Project menu, click Add Reference.
   2. On the COM tab, locate the Object Library for Excel, and then click Select.
      
      For Microsoft Excel 2002 : Microsoft Excel 10.0 Object Library
      
      Note If you have not already done so, it is recommended that you download and install the Microsoft Office XP Primary Interop Assemblies (PIAs). For additional information about Office XP PIAs, click the following article number to view the article in the Microsoft Knowledge Base:
      328912  (http://support.microsoft.com/kb/328912/ ) Microsoft Office XP primary interop assemblies (PIAs) are available for download
      For Microsoft Office Excel 2003: Microsoft Excel 11.0 Object Library
   3. Click OK in the Add References dialog box to accept your selections.
4. On the View menu, click Toolbox, and then drag a Button control onto Form1.
5. Double-click Button1. The code window for the form appears.
6. Add the following code to the top of Form1.vb:

   Imports Microsoft.Office.Interop
   					

7. Replace the following code in the code window

       Private Sub Button1_Click(ByVal sender As System.Object, _
          ByVal e As System.EventArgs) Handles Button1.Click
       End Sub
   					

   with the following:

   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
       Dim oApp As New Excel.Application()
       Dim oBook As Excel.Workbook = oApp.Workbooks.Add
       Dim oSheet As Excel.Worksheet = oApp.ActiveSheet
   
       oSheet = Nothing
       oBook.Close(False)
       oBook = Nothing
       oApp.Quit()
       oApp = Nothing
   
       Debug.WriteLine("Sleeping...")
       System.Threading.Thread.Sleep(5000)
       Debug.WriteLine("End Excel")
   End Sub
   					

8. Press F5 to run the application.
9. Open Windows Task Manager. In Visual Studio, display the Output window to see the debug messages. Click the command button and note that an instance of Excel.exe appears in the Processes list.
10. The instance of Excel still runs in the task list even after the application has finished sleeping. Close the dialog box and note that Excel no longer appears in the Processes list.
11. When you implement the steps in the "Resolution" section, the Office application quits after it releases the last variable. Replace the function in Step 5 with the following code:

      Private Sub NAR(ByVal o As Object)
        Try
          System.Runtime.InteropServices.Marshal.ReleaseComObject(o)
        Catch
        Finally
          o = Nothing
        End Try
      End Sub
    
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim oApp As New Excel.Application()
        Dim oBooks As Excel.Workbooks = oApp.Workbooks
        Dim oBook As Excel.Workbook = oBooks.Add
        Dim oSheet As Excel.Worksheet = oApp.ActiveSheet
    
        NAR(oSheet)
        oBook.Close(False)
        NAR(oBook)
        NAR(oBooks)
        oApp.Quit()
        NAR(oApp)
    
        Debug.WriteLine("Sleeping...")
        System.Threading.Thread.Sleep(5000)
        Debug.WriteLine("End Excel")
    End Sub
    					

private void NAR(object o)
{
    try 
    {
        System.Runtime.InteropServices.Marshal.ReleaseComObject(o);
    }
    catch {}
    finally 
    {
        o = null;
    }
}

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Troubleshooting

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