[BUG] WinError 10038 during hot reload

[niekvleeuwen]

Hi all,

I am experiencing an exception that occurs during hot reloading. First, I thought this occurred because of my upgrade to Python 3.10, but after downgrading back to Python 3.9, the issue still occurs. However, the hot reloading itself seems to work fine.

dash                      2.8.1
dash-bootstrap-components 1.3.1
dash-core-components      2.0.0
dash-html-components      2.0.0
dash-table                5.0.0

My OS version is Windows

2023-03-01 12:00:54 INFO     Dash is running on http://localhost:8050/dashboard/

Dash is running on http://localhost:8050/dashboard/

 * Serving Flask app 'main'
 * Debug mode: on
Exception in thread Thread-2 (serve_forever):
Traceback (most recent call last):
  File "C:\Users\NiekLeeuwenvan\AppData\Local\Programs\Python\Python310\lib\threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "C:\Users\NiekLeeuwenvan\AppData\Local\Programs\Python\Python310\lib\threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\NiekLeeuwenvan\Code\pk-dashboard\venv\lib\site-packages\werkzeug\serving.py", line 766, in serve_forever
    super().serve_forever(poll_interval=poll_interval)
  File "C:\Users\NiekLeeuwenvan\AppData\Local\Programs\Python\Python310\lib\socketserver.py", line 232, in serve_forever
    ready = selector.select(poll_interval)
  File "C:\Users\NiekLeeuwenvan\AppData\Local\Programs\Python\Python310\lib\selectors.py", line 324, in select
    r, w, _ = self._select(self._readers, self._writers, [], timeout)
  File "C:\Users\NiekLeeuwenvan\AppData\Local\Programs\Python\Python310\lib\selectors.py", line 315, in _select
    r, w, x = select.select(r, w, w, timeout)
OSError: [WinError 10038] An operation was attempted on something that is not a socket

I am running the Dash application using the default example:

if __name__ == '__main__':
    app.run_server(debug=True, host='localhost')

Please let me know if this issue is better suited for the Werkzeug issue tracker.

[niekvleeuwen]

During my upgrade to Python 3.10, I reinstalled my virtual environment, which caused Werkzeug 2.2.3 to be installed. Downgrading to Werkzeug 2.2.2 fixes the issue. I created an issue over at the Werkzeug issue tracker.

[savvn001]

Same issue, tried downgrading, this solves the error message in OP but hot reload is not working at all. Did you find this too?

[niekvleeuwen]

@savvn001 I can't remember for sure, but I think the reloading was working correctly after downgrading.