Major Description
Yahoo has as of around mid-2017 discontinued the "download.finance.yahoo.com" API for downloading stock data. There are new APIs that are meant to be used only by browsers (in order to satisfy Yahoo's Terms and Conditions, involving the use of a crumb and cookies). So, the StockTracker tutorial is effectively rendering unusable as of now until replacement logic is available. There is a Visual Basic solution here: http://www.signalsolver.com/wp-content/uploads/2017/10/EmulateURL-V1.0f.txt that is complicated but seems to work at least.