[fabian2k]

I get the following output when trying this with Create React App running:

{"type":"error","data":"Invalid Host/Origin header"}

I don't think I changed any significant settings in CRA, this is pretty close to the default. Not sure what exactly determines whether this works or not.

[stestagg]

Seems to be related to this: https://github.com/webpack/webpack-dev-server/issues/1604

It's not clear (without a lot more digging) what impact the sockjs changes have on this issue.