[OpenStack noVNC]: Code 400, message Client must support ‘binary’ or ‘base64’ protocol [Solved]

As part of OpenStack Yoga release, installed and configured noVNC – a VNC client library based on JavaScript. Essentially, noVNC allows the web browser to act as a VNC client to remotely access a machine. When tried to access the virtual machine console using the console url through browser it showed blank screen as below.

When looked for the errors on the server at /var/log/nova/nova-novncproxy.log found the below complete error message:

2022-11-17 18:06:39.127 2955 INFO nova.console.websocketproxy [-] - Flash security policy server
2022-11-17 18:06:39.127 2955 INFO nova.console.websocketproxy [-] - Web server (no directory listings). Web root: /usr/share/novnc
2022-11-17 18:06:39.127 2955 INFO nova.console.websocketproxy [-] - No SSL/TLS support (no cert file)
2022-11-17 18:06:39.128 2955 INFO nova.console.websocketproxy [-] - proxying from 0.0.0.0:6080 to None:None
2022-11-17 18:06:57.819 3168 INFO nova.console.websocketproxy [-] 192.168.2.15 - - [17/Nov/2022 18:06:57] code 400, message Client must support 'binary' or 'base64' protocol

Solution: After a lot of research on google, found a solution, that explains we need to edit websock.js file to support the subprotocol as below:

Open the file /usr/share/novnc/core/websock.js using your favourite editor

# vim /usr/share/novnc/core/websock.js

Locate the line

this._websocket = new WebSocket(uri, protocols);

Replace with

this._websocket = new WebSocket(uri, ['binary', 'base64']); // protocols);

Save the file and exit

Restart the openstack-nova-novncproxy service as below:

# systemctl restart openstack-nova-novncproxy

Now you can successfully access the console url on the browser.