Yes, it looks like Yahoo! discontinued (private, mostly undocumented) Yahoo Finance API, which many used for their currency data. All answers seem to be coming back "Not a valid parameter". I believe there is a chance that they can enable it again, but they do not officially support this API anywhere, as far as I can tell.
I created Open Exchange Rates about five years ago, and our exchange rate API now supports a community of tens of thousands of developers - and their tens of millions of users - with accurate and up-to-date information.
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