stock price retrieval not working

[Dino Carubia]

Installed latest version of gnucash (2.6.18).Ran "Install online price retrieval..."
When I try to update stock prices I get the following:"There was an unknown error while retrieving the price quotes."
I have tried to use the "multiple sources" option, but I still cannot get any prices.
If I try the command line I get the following result:C:\Program Files (x86)\gnucash\bin>perl gnc-fq-dump -v yahoo ibmNo results found for stock ibm.
I was last able to retrieve prices successfully on October 29th, 2017.
Any advice would be appreciated!