SockJS-Client version mismatch

Created by: holloway

If you start the dev server and browse to,

/sockjs-node/iframe.html

You'll see the fallback for when a browser can't establish a websocket connection. It references a CDN version of SockJS-Client 1.0.1

<script src="https://cdn.jsdelivr.net/sockjs/1.0.1/sockjs.min.js"></script>

But the chosen SockJS-Client version elsewhere in react-dev-tools is 1.0.3 so it fails with this error,

sockjs.min.js:2 Uncaught Error: Incompatibile SockJS! Main site uses: "1.0.3", the iframe: "1.0.1".s

SockJS-Client 1.0.3 was chosen at https://github.com/facebookincubator/create-react-app/blob/master/packages/react-dev-utils/package.json#L31

If you disable websockets in your browser, or have a proxy that doesn't handle websockets (like I do), you can reproduce this error.

You could fix this by downgrading the package.json to version 1.0.1, or by using a fork of sockjs-node that matches the version you want by applying this patch https://github.com/holloway/sockjs-node/pull/1/commits/6c1a7b6bd68c5c2d5f4e39e3a8567d7d6dd440ea

Incidentally the current version of SockJS-Client is 1.1.1.