I\'ve tried going to the URL listed for the official package source with my browser and I only get a
I had similar issue with VS2015. The default package feed (https://www.nuget.org/api/v2/curated-feeds/microsoftdotnet/) returned no results. Switched to https://www.nuget.org/api/v2 and was able to find packages again.
Tools->Options->Nuget Package Manager->Package Sources and add new Package Source.