I have been using the Yahoo Fantasy Sports API for several years now, but over the last 24 hours, I've been getting server errors. Nothing has changed in my code, and other users are confirming similar issues here. The Yahoo support staff redirected us to their YQL support page, which tells people to post their questions on SO. Has this API been silently killed? Is there a new version?
I ran into this issue and it seems that Yahoo has basically silently deprecated / removed support for oauth, so you have to switch to oauth2 to in order to use many of their APIs.
In my case the yahoo_oauth python library worked quite well for upgrading to 2.0.