'Access-Control-Allow-Private-Network' header Issue When Developing Locally

[sambessey]

Hi

I am using Socket.io in a locally developed Node instance and getting the following error in Chrome (My 'Client' in this case is a Chrome Extension):

Access to XMLHttpRequest at 'http://localhost:8888/socket.io/?token=null&EIO=4&transport=polling&t=OaRktub' from origin 'https://docs.google.com' [Where my Chrome Extension runs] has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Private-Network' header was present in the preflight response for this private network request targeting the local address space.

Is there some configuration flag I should be setting on my local server to return this header? as I can find very little written on this but this must affect everyone developing locally. I have tried setting the header just after I initialize socket.io by adding the following, but to no avail

io.engine.on("headers", (headers) => { headers["Access-Control-Allow-Private-Network"] = true; });

I have tried everything I can think of to attach the 'Access-Control-Allow-Private-Network' header to the response, but I must be doing something wrong as I can never get around this no matter what I do.

Thanks

[darrachequesne]

Hi! If I understand the article here this header is not needed anymore in new versions of Chrome. Could you please check?