.net core signalr to mvc signalr

Question

Hello im trying to migrate a project from .net core to mvc and i have some issues about signalr.

This work on new mvc project.

Reference the auto-generated proxy for the hub.  
var chat = $.connection.chatHub;
// Start the connection.
$.connection.hub.start().done(function () {
    alert("done");
});

But this one which is from the old(.net core) project doesnt work. Error is: Uncaught ReferenceError: signalR is not defined

var connection = new signalR.HubConnectionBuilder().withUrl("/chatHub").build();

connection.start().then(function () {
    console.log('SignalR Started...');
    viewModel.roomList();
    viewModel.userList();
    setTimeout(function () {
        if (viewModel.chatRooms().length > 0) {
            viewModel.joinRoom(viewModel.chatRooms()[0]);
        }
    }, 250);
}).catch(function (err) {
    return console.error("!!!!!" + err);
});

browser/signalr.js the first one define signalR but this time the error is: Error: Failed to complete negotiation with the server: Error

Answer 1

My main problem was in my constructor method. I could not trigger server side methods. My old project want initialize variables and there was no try catch block. So i deleted constructor method. Then it worked.