I am using singnalR hub in asp.net mvc 4 application. I got this following error it was cleared by referencing signalR hubs in the page.
Solution:
If you are using signalR in the page, make sure you need to reference the SignalR hub like this,
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>
<script src="~/Scripts/jquery.signalR-2.2.1.min.js"></script>
<script src="/signalr/hubs" type="text/javascript"></script>