At the moment (18/5/2017) we are not able to get pricing data from Yahoo servers. The Yahoo server gives back the message “Will be right back” since Monday.
https://forums.yahoo.net/t5/Yahoo-Finance-help/bd-p/finhelp
We are working on this problem and will probably add a second data provider in the future for the case Yahoo does not work.
We apologize for the inconvenience!