NuGet Package Manager: "No packages found" even though the package exists
<p>After updating Visual Studio to 2015 Update 2 I kept getting a "No packages found" error in NuGet Package Manager, despite browsing/searching for packages that I knew existed and which could be added from the Package Manager Console.</p>

<p>This is frustrating as the NuGet site clearly shows the packages are available. As a workaround I can install them via the Package Manager Console - but the GUI just shows "No packages found".</p>