We got several complaints today that downloading data from Yahoo does not work anymore. The reason is that Yahoo switched their servers to a new HTTPS protocol last weekend.
We've just uploaded a new beta version, 1.56.4, which downloads Yahoo data with the new protocol. You can get it from http://opserver.de/down/ZorrroBeta.zip.
Alternatively, you can still use your old version, but download Yahoo data from Quandl, f.i. assetHistory("YAHOO/AAPL",FROM_QUANDL);
You must register at Quandl for getting a Quandl key. Also, Quandl does support Stocks, but not all ETFs in their Yahoo database.
Update: For downloading all the Z8 assets with the beta version, you can use a small script like this: