Hi Chirag, 
I need your assistance below.
I have created platform event and trying to subscribe through visualforce page. I am getting below mentioned errors.

12:53:38.271 Appending message type to URI /cometd/49.0/ is not supported, disabling 'appendMessageTypeToURL' configuration
jQuery:4055 Uncaught Illegal state: handshaken
(anonymous) @ jQuery:4055
setTimeout (async)
jQuery.readyException @ jQuery:4054
(anonymous) @ jQuery:4074
mightThrow @ jQuery:3762
process @ jQuery:3830
setTimeout (async)
(anonymous) @ jQuery:3868
fire @ jQuery:3496
fireWith @ jQuery:3626
fire @ jQuery:3634
fire @ jQuery:3496
fireWith @ jQuery:3626
process @ jQuery:3850
setTimeout (async)
(anonymous) @ jQuery:3868
fire @ jQuery:3496
fireWith @ jQuery:3626
fire @ jQuery:3634
fire @ jQuery:3496
fireWith @ jQuery:3626
ready @ jQuery:4106
completed @ jQuery:4116
cometd:885 WebSocket connection to 'wss://awr--raguramans--c.visualforce.com/cometd/49.0/' failed: Error during WebSocket handshake: Unexpected response code: 405
_websocketConnect @ cometd:885
_send @ cometd:1002
WebSocketTransport._self.send @ cometd:1157
_send @ cometd:1646
_handshake @ cometd:1862
CometD.handshake @ cometd:2540
CometD.init @ cometd:2527
(anonymous) @ LeadPlatformEvent:19
mightThrow @ jQuery:3762
process @ jQuery:3830
DevTools failed to load SourceMap: Could not load content for https://awr--raguramans--c.visualforce.com/javascript/1592237695000/sfdc/source/main.js.map: 

Visual page code:

<apex:page >
  <!-- Begin Default Content REMOVE THIS -->
  <h1>Congratulations</h1>
  This is your new Page
  <!-- End Default Content REMOVE THIS --> <div id="content">
        
    </div>
    <apex:includeScript value="{!$Resource.cometd}"/>
    <apex:includeScript value="{!$Resource.jQuery}"/>
    <apex:includeScript value="{!$Resource.json2}"/>
    <apex:includeScript value="{!$Resource.jQuery_cometd}"/>
  
    
    <script type="text/javascript">
    (function($){
        $(document).ready(function() {
     $.cometd.init({
    url:  window.location.protocol+'//'+window.location.hostname+'/cometd/49.0/',
    requestHeaders: { Authorization: 'OAuth {!$Api.Session_ID}'}
});        

            $.cometd.handshake();
            $.cometd.addListener('/meta/handshake', function(message) {
                $.cometd.subscribe('/event/Event_On_Leads__e', function(message) {
                
                    console.log('testing subscribed');
                    var div = document.getElementById('content');
                    
                    div.innerHTML = div.innerHTML + '<p>Notification </p><br/>' +
                        'Streaming Message ' + JSON.stringify(message) + '</p><br>';
                });
            });
            
        });
    })(jQuery)
    </script>

</apex:page>