C# XMLDocument Save - Process cannot access the file because it is being used by another process

Question

I'm having trouble saving my XML file after I have called load. This function is called twice - once when "toSave" is set to false, and then the second time is when it is set to true. On the second time round, the save causes an exception. I tried adding a Dispose and Close call to the XMLReader but nothing seems to help. Here is the code:

// Check if the file exists
if (File.Exists(filePath))
{
    try
    {
        // Load the file
        XmlReaderSettings readerSettings = new XmlReaderSettings();
        readerSettings.IgnoreComments = true;
        XmlReader reader = XmlReader.Create(filePath, readerSettings);

        XmlDocument file = new XmlDocument();
        file.Load(reader);

        XmlNodeType type;
        type = file.NodeType;
        if (toSave)
            ModifyXMLContents(file.FirstChild.NextSibling, null);
        else
            PopulateNode(file.FirstChild.NextSibling, null);

        // Save if we need to
        if (toSave)
            file.Save(filePath);

        reader.Dispose();
        reader.Close();
    }
    catch (Exception ex)
    {
        // exception is: "The process cannot access the file d:\tmp\10.51.15.2\Manifest.xml" because it is being used by another process
        Console.WriteLine(ex.Message);
    }
}

Any help would be greatly appreciated.

Answer 1

The XmlReader you created is still open when you try to save it, and hence it is locking the file and preventing the save.

Once loaded into the XmlDocument , you don't need the reader anymore, so you can close/dispose it before you attempt the save and then the save should work.

For example:

XmlReaderSettings readerSettings = new XmlReaderSettings();
readerSettings.IgnoreComments = true;            

XmlDocument file = new XmlDocument();

using (XmlReader reader = XmlReader.Create(filePath, readerSettings))            
    file.Load(reader);

/* do work with xml document */

if (save)
    file.Save(filePath);

Answer 2

For me this was caused by the file being written out into a directory with MANY (100k) other files. Once I cleared out all the other files the problem went away. NTFS appears to get cranky with very large numbers of files in a single folder.