The source at nuget.org is unreachable?
问题 I'm trying to install SignalR in my C# project, but all I get when running install-package Microsoft.AspNet.SignalR is: The source at nuget.org [https://www.nuget.org/api/v2/] is unreachable. Falling back to NuGet Local Cache(...) At line:1 char:1 + install-package Microsoft.AspNet.SignalR + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : NotSpecified: (:) [Install-Package], InvalidOperationException + FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands