Can't understand why SqlConnection is returning System.NullReferenceException

Question

This is baffling me. I have this line of code that is causing the problem

string prodID = DBTools.getProdID(args[0]).ExecuteScalar().ToString();

When I run this in my program I eventually get an error.

public static SqlCommand getProdID(string server)
    {
        string sql = "SELECT Password FROM UTrainID";
        SqlCommand cmd = createCmd(server, "AACSMapping", sql);
        cmd.Connection.Open(); // this generates the System.NullReferenceException
        return cmd;
    }

The thing that is baffling me about this is that I have a UnitTest that tests this that works perfectly.

 [TestMethod]
    public void getProdIDTest()
    {
        string ID = UTrain.DBTools.getProdID("PN1173312").ExecuteScalar().ToString();
        Assert.IsTrue(ID.Equals("XXXXXXXXX"));
    }

When I run this console application I've checked that the Args[] values are right ie it's the same value that I have in the UnitTest. The other things that is bothersome about this is that when I try to debug it by stepping through the code it works fine! That tells me that it's a timing problems of some type but that's beyond me. Here is the code that creates the actual connection.

public static SqlConnection createConnection(string server, string initcat)
    {
        try
        {
            SqlConnectionStringBuilder strBuild = new SqlConnectionStringBuilder();
            strBuild.IntegratedSecurity = true;
            strBuild.InitialCatalog = initcat;
            strBuild.DataSource = server;
            SqlConnection conn = new SqlConnection(strBuild.ConnectionString);
            return conn;
        } // end try
        catch (Exception e)
        {
            writeErrorMessage(e, "Could not create connection.");
            return null;
        }
    }

I don't know that it makes any difference but the reason I break the code up like this is I'm connecting to a number of different databases so it makes it easier to do it like this I feel.

Answer 1

Thanks for the comments. I finally found the problem. It was throwing a error that was being written to the error log file. It was a "Type initializer for SqlConnection threw an exception" When I searched for that error message most concerns were with the app.config file. I checked that and it was not formatted correctly. There was an extra >. I can see why the unit test might have worked when running unit tests I guess they wouldn't load the app.config file, but I still don't understand why stepping through with the debugger would work correctly?