Signal R error

[arun1998]

Hello El Vany

I downloaded the project and tried it out. After making a few adjustments, the SignlaRCore.Web project runs successfully. However, when I click on the sell button, I am receiving a javascript error - Cannot send data if the connection is not in the 'Connected' State.
at c.HttpConnection.send (signalr-client-1.0.0-alpha2-final.min.js:1)
at signalr-client-1.0.0-alpha2-final.min.js:1
at new Promise ()
at c.HubConnection.invoke (signalr-client-1.0.0-alpha2-final.min.js:1)

When the page loads, it does say connection opened. I tried a lot but am not able to resolve this. Can you please let me know what the issue could be? Thanks