Word Automation - File is in use by another application or user.

Programmer Question

I have a WinForms application where I am using Word Automation to build documents via a template, and then save them to the database. After the document is created, I retrieve the document from the database, write it to the file system in a temp directory, and then open the document using the Word Interop services.

There is a list of documents loaded and the user can open only 1 instance of each document, but can open multiple different documents simultaneously. I don't have any problems with opening, saving, and closing when they open 1 document, however, when they open multiple documents simultaneously, I get the following error when closing any of my instances of Word:

The file is in use by another application or user. (C:\...\Templates\Normal.dotm) 
This error is commonly encountered when a read lock is set on the file that you are attempting to open.

I am using the following code to open the document and handle the BeforeDocumentClosed event:

public void OpenDocument(string filePath, Protocol protocol, string docTitle, byte[] document)
{
    _protocol = protocol;
    documentTitle = docTitle;
    _path = filePath;

    if (!_wordDocuments.ContainsKey(_path))
    {
        FileUtility.WriteToFileSystem(filePath, document);

        Word.Application wordApplication = new Word.Application();
        wordApplication.DocumentBeforeClose += WordApplicationDocumentBeforeClose;

        wordApplication.Documents.Open(_path);

        _wordDocuments.Add(_path, wordApplication);
    }
    _wordApplication = _wordDocuments[_path];
    _currentWordDocument = _wordApplication.ActiveDocument;

    ShowWordApplication();
}

public void ShowWordApplication()
{
    if (_wordApplication != null)
    {
        _wordApplication.Visible = true;
        _wordApplication.Activate();
        _wordApplication.ActiveWindow.SetFocus();
    }
}

private void WordApplicationDocumentBeforeClose(Document doc, ref bool cancel)
{
    if (!_currentWordDocument.Saved)
    {
        DialogResult dr = MessageHandler.ShowConfirmationYnc(String.Format(Strings.DocumentNotSavedMsg, _documentTitle), Strings.DocumentNotSavedCaption);

        switch (dr)
        {
            case DialogResult.Yes:
                SaveDocument(_path);
                break;
            case DialogResult.Cancel:
                cancel = true;
                return;
        }
    }

    try
    {
        if (_currentWordDocument != null)
            _currentWordDocument.Close();
    }
    finally
    {
        Cleanup();
    }
}

public void Cleanup()
{
    if (_currentWordDocument != null)
        while(Marshal.ReleaseComObject(_currentWordDocument) > 0);

    if (_wordApplication != null)
    {
        _wordApplication.Quit();
        while (Marshal.ReleaseComObject(_wordApplication) > 0);
        _wordDocuments.Remove(_path);
    }
}

Does anyone see anything wrong that I am doing to allow opening of multiple documents at the same time? I am fairly new to Word Automation and the Word Interop services, so any advice is appreciated. Thanks.

Find the answer here