App.config - LocalSqlServer connection string

It is possible to have more than just the LocalSqlServer in your Machine.config. e.g. I just ran my app on a computer with a MySql connection in Machine.config

You can use the ElementInformation property of the ConnectionStringSetting to determine where it came from:

foreach (ConnectionStringSettings c in ConfigurationManager.ConnectionStrings)
    ElementInformation elementInfo = c.ElementInformation;
    String source = elementInfo.Source;

    if (source == null)
        Console.WriteLine("{0} {1} {2}", c.Name, elementInfo.Source, c.ConnectionString);

It is defined in the Machine.config global file located at


It is generated when you install the NET.Framework and is needed by tools that work on the ASPNETDB

If you don't need it, you could try to add this to your app.config


or also

<remove name="LocalSqlServer" />

I really suggest to not change anything in Machine.Config unless you know the side effects.