Chrome Websockets CORS policy

There is no browser enforced CORS with WebSocket. Here are 2 things that can go wrong (assuming you use both HTTPS and WSS):

• the server enforces an Origin. The Origin HTTP header is set by the browser to the origin of the HTML page containing the JavaScript that is opening the WebSocket connection. A server MAY check that header and deny. But since you say other browsers are working (which?), this is unlikely
• since you are using wss, the server certificate MUST be completely valid, and acceptable to the browser without any user interaction. Is this the case?

I came across this issue again. I still haven't figured out why, but making an OPTIONS (or any other) request to the subdomain first allows the connection to be opened.

This only seems to be a problem with wss connections, and has popped up across multiple domains and certificates.