Flask SocketIO CORS Error After Deploy

[selmanbaskaya]

ERROR: Access to XMLHttpRequest at 'https://blabla.com/socket.io/...' from origin 'https://blabla.com' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

I am using Flask SocketIO with VueJs. Everything works fine in my local, but after deploy I started getting CORS error.
I checked the documentation but couldn't find the cause of the error.
** I added cors_allow_origins='*' option for the socket io initialization.

my init.py file is here:
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app = Flask(name)
CORS(app)
socketio = SocketIO(app, cors_allowed_origins="*")
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.
.

my main.py file is here:
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if name == "main":
socketio.run(app)

[miguelgrinberg]

I think your attempt to obscure your real hostname is complicating this issue, because I assume you are not really using https://blabla.com?

The error as you are showing it makes no sense, because it complains about a different origin, while in fact the two URLs shown in the error message have the same origin.

[miguelgrinberg]

How you start the server depends on the async mode that you are using. See the documentation. The --workers is probably wrong, and the --timeout is unnecessary and might be covering other problems that you have in your application.

[selmanbaskaya]

hmm, actually everything works fine with workers and timeout. requests are sent to all other endpoints in the project. I get an error only when I want to connect to socketio.

[selmanbaskaya]

When I want to connect to socketio, "Access-Control-Allow-Origin:" key does not appear in response header. twinide.com appears in the response header of the other request.

[miguelgrinberg]

You have to debug this yourself. You told this library to include the CORS headers in the responses, and you do have this working when you connect directly to your server in your local set up. Something in your production server must be filtering these headers out. What other option is there?

Also, regarding the timeout, it's really none of my business, but having a timeout of 333 hours is definitely not something I would consider normal. The default 30 second timeout in Gunicorn is sufficient in most cases.

[selmanbaskaya]

You are right, thank you for answering my questions for 1 week. When I find the solution, I will share it here.

Also, I will consider your suggestion regarding timeout.