title: .Net Core SignalR cannot add or use in startup
body: <p>Ive recently come back to an old .Net Core application which was using SignalR.</p>
  
  <p>I think at the time the only SignalR NuGet package available for .Net Core applications was a preview. And it worked.</p>
  
  <p>Im now on a new machine and dont know what the preview feed was for this package so ive uninstalled it and installed this:</p>
  
  <pre><code>&gt; Install-Package Microsoft.AspNet.SignalR.Core -Version 2.4.1
  </code></pre>
  
  <p>Everything seems fine with a few namespace changes apart from these two errors in the Startup.cs file.</p>
  
  <blockquote>
    <p>Error CS1061  'IServiceCollection' does not contain a definition for
    'AddSignalR' and no accessible extension method 'AddSignalR' accepting
    a first argument of type 'IServiceCollection' could be found (are you
    missing a using directive or an assembly reference?)</p>
    
    <p>Error CS1061  'IApplicationBuilder' does not contain a definition for
    'UseSignalR' and no accessible extension method 'UseSignalR' accepting
    a first argument of type 'IApplicationBuilder' could be found (are you
    missing a using directive or an assembly reference?)</p>
  </blockquote>
  
  <p>I've looked around and there isn't much available for me, other than someone suggesting you need to install <code>Microsoft.AspNetCore.SignalR.Http</code> which I cant find. Someone else suggested you need to install this:</p>
  
  <pre><code>Install-Package Microsoft.AspNetCore.SignalR.Client -Version 1.1.0
  </code></pre>
  
  <p>Which I've tried, but the errors remain, how do I get these to go away?</p>
  
  <p><a href="https://i.stack.imgur.com/vEr4p.png" rel="noreferrer"><img src="https://i.stack.imgur.com/vEr4p.png" alt="enter image description here"></a></p>