Microsoft
Microsoftmsousa19imperial I looked into the stocks from your book. According to MSN Money, most of the #VALUE you are getting are because the first trade on record happens after 2/28/2020. So we should better adjust our error message in this instance to say "The days between start_date and end_date are non-trading days, such as holidays, weekends, or days prior to the first trade of this instrument"
Then for the N/A errors, this represents a valid trading day, but the stock in question is not traded on those days. This is a common error for low volume stocks that are not traded daily. In other words, no data is available for that day even though it is a valid trading day.
Lastly, we have some mutual funds and index funds that we do not have license to report on the History. This is commonly shown as a "Stock argument not found" error, and there isn't anything we can do to correct it at this time.
Hope that helps,
--Kaycee Sue