I am trying to install SignalR in Visual Studio 2010 professional project. But I am getting this error:
Could not install package 'Microsoft.Owin.Security 2.1.0'. You are trying to install this package into a project that targets '
.NETFramework,Version=v4.0', but the package does not contain any assembly references or content files that are compatible with that framework. F
or more information, contact the package author.
Try installing a different version of signal r with this command (via nuget package console) 'install-package Microsoft.AspNet.SignalR -Version 1.1.3'. Latest version of signalr requires .net4.5
I meet this issue and solving it by upgrade my project's target .Net Framework version to 4.6.1 (latest)
I stumble into the same problem and I give you some additional recommendations in case someone cannot solve it.
First at all, some libraries like SignalR are always working in tandem with last versions of the framework and some other libraries. It's normal you create a project targeting let's say OWin 2.1 and few months later in a package restore you get the last one upgrading everything.
Second, it's very normal to create a library with an older framework version by mistake or if you don't use the Visual Studio IDE you don't even realize some libraries target a different framework version. This is my case using SharpDevelop that created most of my Libraries pointing to C# 4.0.
Review every project in your solution; find online the dependencies of the project and the targets. Unfortunately, there's not any common pattern for this, SignalR doesn't publish the dependencies neither in the package manager or the GitHub project. https://github.com/SignalR/SignalR/releases
I had the same error, en VS 2013 with a web project 4.0 framework, I ran the 'install-package Microsoft.AspNet.SignalR -Version 1.1.3'command and the package has installed sussefull
来源：https://stackoverflow.com/questions/28807273/installing-asp-net-signalr-error-while-installing