I build different stock portfolios. Sometimes QT tells me a portfolio has an error and would I like to use the repaired portfolio. Sometimes, I can figure out what happened, but not always. What causes a repair???
In older Quanttrader versions there was a bug which allowed to add an ETF without additional parameters like data source or currency. This is fixed in the newer versions of QT and if QT finds some incomplete ETF or stock data it automatically fixes these errors.