[Python] Websocket error when running "streamlit hello" on localhost

Streamlit hello opens up a browser with a silhouette of some flashing page elements, kind of looks like it's trying to load but can't connect. The command line I used to run streamlit hello shows a websocket error. Chrome also shows a websocket error in the developer tab. The error messages in cmd and the browser both repeat continuously, reoccurring every few seconds while the process runs.

cmd:

streamlit hello


browser:

http://localhost:8501/


Command line error:

2024-11-10 12:57:40.144 Uncaught exception
Traceback (most recent call last):
File "C:\Users\myUsername\AppData\Local\Programs\Python\Python310\lib\site-packages\tornado\http1connection.py", line 278, in _read_message
delegate.finish()
File "C:\Users\myUsername\AppData\Local\Programs\Python\Python310\lib\site-packages\tornado\routing.py", line 268, in finish
self.delegate.finish()
File "C:\Users\myUsername\AppData\Local\Programs\Python\Python310\lib\site-packages\tornado\web.py", line 2399, in finish
self.execute()
File "C:\Users\myUsername\AppData\Local\Programs\Python\Python310\lib\site-packages\tornado\web.py", line 2421, in execute
self.handler = self.handler_class(
File "C:\Users\myUsername\AppData\Local\Programs\Python\Python310\lib\site-packages\tornado\websocket.py", line 220, in __init__
super().__init__(application, request, **kwargs)
File "C:\Users\myUsername\AppData\Local\Programs\Python\Python310\lib\site-packages\tornado\web.py", line 214, in __init__
super().__init__()
File "C:\Users\myUsername\AppData\Local\Programs\Python\Python310\lib\typing.py", line 1422, in _no_init_or_replace_init
cls.__init__(self, *args, **kwargs)
TypeError: WebSocketHandler.__init__() missing 2 required positional arguments: 'application' and 'request'


Chrome developer tab error:

main.754d974e.js:19 WebSocket connection to 'ws://localhost:8501/\_stcore/stream' failed:
connectToWebSocket @ main.754d974e.js:19

WebsocketConnection WebSocket onerror
a @ mainl.754d974e.js:10


I am using Python 3.10. Streamlit is a fresh install with pip, which I also updated.

I am running WLS Ubuntu (Linux subsystem) on my machine, but I don't think that should be relevant since Python is installed on windows and all the commands and browsers I am using are on my main windows system.

I tried turning off Norton antivirus stuff. I tried turning off all Chrome extensions and also tried the same in Edge. I tried creating a Python virtual environment. I tried running the command prompt as an administrator.

I did google the error message and that is how I found the list of resolutions that I mentioned as having already tried. Many of the suggestions relate to writing custom code, but I'm just executing the built-in "hello world" feature of streamlit without any custom work. I don't see how TLS could be the cause as I'm not using https to connect in the browser. The closest thing to my error that I found was the below, but it does not lead to a resolution: github.com/streamlit/streamlit/issues/9140

This is some kind of basic environment setup issue I feel, because it is a built-in hello world function within streamlit.

Here is how I created and setup my virtual environment:

python -m venv strl_venv
strl_venv\Scripts\activate.bat
pip install streamlit
python -m streamlit hello


This did not solve the problem.

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