HTTP ERROR 403 - about lifefinances HOT 3 CLOSED

The reason for 403 error can be found here https://stackoverflow.com/questions/72795799/how-to-solve-403-error-with-flask-in-python

Mac OSX Monterey (12.x) currently uses ports 5000 and 7000 for its Control centre hence the issue.
Try running your app from port other than 5000 and 7000

So I tried several unused ports like 8000:

if __name__ == "__main__":
    URL = "http://127.0.0.1:8000/"
    webbrowser.open(URL)
    print("app: socketio.run(app, port=8000, debug=True)")
    socketio.run(app, port=8000, debug=True)
    print("app: End __main__")

For each port I tried, a browser tab opened with This site can’t be reached; 127.0.0.1 refused to connect., then a few seconds later another browser tab opened with Not Found.

And the server output showed that the server started two times:

$ python app.py
app: socketio.run(app, port=8000, debug=True)
 * Restarting with stat
app: socketio.run(app, port=8000, debug=True)
 * Debugger is active!
 * Debugger PIN: 726-010-831
(57021) wsgi starting up on http://127.0.0.1:8000
(57021) accepted ('127.0.0.1', 61924)
(57021) accepted ('127.0.0.1', 61925)
127.0.0.1 - - [29/Jul/2023 20:10:05] "GET / HTTP/1.1" 404 355 0.001925

from lifefinances.

I will temporarily give up on MacOS, and try Windows 10 instead. Please see follow-up issue #143.

from lifefinances.

To free up flask's default port 5000 I disabled System Preferences > Sharing > AirPLay Receiver on MacOS 12.6.7
These 2 cases continued to fail:

1. with __main__ section commented-out:
   -- app.py terminated with no output
2. with comments removed from __main__, and default port 5000 specified:
   -- 1st browser tab opened with ERR 403
   -- 2nd browser tab opened with ERR 404

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