Hello Mark,
I received a WinInet error code 12039 "A redirect request will change a non-secure to a secure connection" when trying to retrieve historical prices from TSP. The error started sometime over the last week or so. (Maybe a little more)
I attached a screen capture of just the error dialogue boxes.
I just verified that the same error occurs retrieving the current price as well. The error is from TSP.gov
Jason