title: SignalR .Net Client fails with 500 server error on device, on simulator works fine
body: <p>I'm trying to implement a chat in my app, with azure asp.net web api on back-end and xamarin ios on front-end.</p>
  
  <p>So on back-end I configure my hub with this lines:</p>
  
  <pre><code>        var hubConfiguration = new HubConfiguration();
          hubConfiguration.EnableDetailedErrors = true;
          app.MapSignalR("/signalr", hubConfiguration);
  </code></pre>
  
  <p>and here is my hub source:</p>
  
  <pre><code>[HubName("Chat")]
  public class Chat : Hub
  {
  
      public Task JoinRoom(string roomName)
      {
          return Groups.Add(Context.ConnectionId, roomName);
      }
  
      public Task LeaveRoom(string roomName)
      {
          return Groups.Remove(Context.ConnectionId, roomName);
      }
  
      public Task Send(string message, string room)
      {
          return Clients.OthersInGroup(room).addMessage(message);
      }
  }
  </code></pre>
  
  <p>on xamarin ios client everything is pretty simple too:</p>
  
  <pre><code>[Preserve(AllMembers=true)]
  public class Msg
  {
      public string txt { get; set; }
  }
  
  public class Client
  {
      private readonly string _userName;
      private readonly HubConnection _connection;
      private readonly IHubProxy _proxy;
  
      public event EventHandler&lt;string&gt; OnMessageReceived;
  
      public Client(string userName)
      {
          _userName = userName;
          _connection = new HubConnection("http://mywebsite.azurewebsites.net/");
          _connection.ConnectionToken = NetManager.Instance.token.access_token;
          _proxy = _connection.CreateHubProxy("Chat");
      }
  
      public async Task Connect()
      {
  
          await _connection.Start();
  
          _proxy.On("messageReceived", (Msg platform, Msg message) =&gt;
              {
                  if (OnMessageReceived != null)
                      OnMessageReceived(this, string.Format("{0}: {1}", platform, message));
              });
  
          Send("Connected");
      }
  
      public Task Send(string message)
      {
          return _proxy.Invoke("Send", _userName, message);
      }
  }
  </code></pre>
  
  <p>So if I connect to server from ios simulator -- it works fine, but when I try to do this from my ipad device -- it crashes with internal server error on line ('await _connection.Start();')</p>
  
  <p>I have already checked server with debugger, but no exceptions raised there, and logs are clear.</p>
  
  <p>Any ideas how to fix this will be very helpful!</p>
  
  <p>[<strong>Upd</strong>]
  Some new server logs:</p>
  
  <p>FROM SIMULATOR:</p>
  
  <p>2015-09-27 03:29:39 IBYB GET /signalr/negotiate clientProtocol=1.4&amp;connectionData=[%7B%22Name%22:%22chat%22%7D]&amp;connectionToken=1qZRVTwNMqgGiI8iPpJ9oaPPCeLhHti3UXZR4HYsw2_7SGzOj44WRt8qzBFPRELZu6zk33-8uS7MNaq5K7N5qA2BR1IgzUf8CP9ihoGbjcwtXpFkdyh5gNqFBTHIRSgc2yto5_AOGUok_opd4B9FjAmOhgQlHF_myf28oBBYJxaXZ5iJOXFpI33k6pmQASRvveW-kBRX_89BF2mxAqFkZmVh3_MCo2gWP-NRZZFtMd8ZoxYHnGhyGNVsiiN1KaTHB1xAakP7HZjLpWg7SigfMvtKW0g3eXBsAr1wCJsAKIRjCaMAQFGV0BkKfYztRXvz4QbSXmIBXpKtviYamOqih4-LQJyywwVNh_Djt9H0wYIZmVO565G4ZNKzQfSkK6jMFQz6GfFf_OSlUJIz-0IXsQ7t2kP5VfqVrRu5KK7pyqtZJE5Y4HikRkh6DP8GIYBiXZclmBrpwWhUYVq5P3J2zhDYDNW2GiB95xnRjzXSjPQ&amp;noCache=ccc35de3-5b7a-49ac-bf89-f15145d2634f&amp;X-ARR-LOG-ID=bce175df-8246-4e75-8887-707a7386e1ee 80 - 89.179.240.94 - - - ibyb.azurewebsites.net 200 0 0 942 1718 1093</p>
  
  <p>FROM DEVICE:</p>
  
  <p>2015-09-27 03:35:02 IBYB GET /signalr/negotiate clientProtocol=1.4&amp;connectionData=[%7B%7D]&amp;connectionToken=YIZWqEe7AHvZHwb_aG7jOA9y_NFwUTBuLWSP46q8yh2rQMcjASbsp7VWlZ0Jzo_Z-n230IlhnOHZKm8kJr72ejLF-4LMopwyfZaWmsKNAy6cTd5uyU-76WoXsd2gpmpEJp8A0vMXe2HeLMIvH2Ckw6NIamEbu_uQvHRplkGeUhqGbTQU04dsU47ksebG_zh9XTtLGY9767CiwCYBg_Zk3aFgfrSvzPBiijfmIP9mUhz2ViAigyPeDeOE6WYRgtkkOIGMXGOoS5vQODHMUtiMaoV-w-jcCWtjHzzaObKNeX6zAsB0aJDc9_7fJAoBER7Jd6g0FOuEDvo8D95f1vA8j2SxbBgR4SFIzBDo_JfzO_TbPA6a2FR-ruw3yZHMidmcz3XQWb3vL5a0BPntzL9MPiVgvuhvkXfiRoDrRbzn2YXSqWrN-eEdjsF_WX-LMUc1JyKkjcHP00EAw3kocDWbnXaPqirsSvC5SZ7KY1u63BU&amp;noCache=daae80e6-d209-42c9-8780-35d00fd8208c&amp;X-ARR-LOG-ID=b1aad3d6-7df8-4828-a89c-665d8b550c0c 80 - 89.179.240.94 - - - ibyb.azurewebsites.net 500 0 0 11369 1676 281</p>
  
  <p>So somehow, don't know why from device sends empty group name 
  (1) :[%7B%22Name%22:%22chat%22%7D]
  (2) :[%7B%7D]</p>
  
  <p>Seems like json serializer problem, but how can I fix that?</p>