Question

I’m confused as to why setting the datasource of a datagridview control to null, would cause an “object reference not set to an instance of an object” error. Thanks in advance

while (xmlReader.Read())
{
    if ((xmlReader.NodeType == XmlNodeType.Element) && (xmlReader.Name == "deposits"))
    {
        oDeposit.DepAmt = Convert.ToDouble(xmlReader.GetAttribute("depamount"));
        oDeposit.DepDate = Convert.ToDateTime(xmlReader.GetAttribute("depdate"));
        oDeposit.DepositId = Convert.ToInt32(xmlReader.GetAttribute("depid"));

        oCustomer.addDeposits(oDeposit);
        **dgvDeposits.DataSource = null;**
        dgvDeposits.DataSource = oCustomer.Deposits;            
    }
}

Answer 1

You should use this instead of setting DataSource to null:

dgvDeposits.DataSource = typeof(Deposit);

Please check following question it might have an explanation for your exception.