Can't install any NuGet Package if at least one Source is not available

Question

The following problem does not exist in VS2013 (Premium),I can only reproduce it in VS2015 (Enterprise)

I\'ve added a custom NuGet package source. If that source if

Answer 1

This is an old question so I'm surprised the workaround from the bug report wasn't added here. To save reader a click:

1. From within Visual Studio, open Tools -> Options -> NuGet Package Manager -> Package Sources
2. Untick all of the package sources that are unavailable, leaving just the public NuGet entries.
3. Install your packages as normal

Once you're back in your office follow steps 1 and 2 again but this time make sure everything is checked.