Firefox cannot establish the websocket connection but other browsers and firefox private browsing can.

[kj4tmp]

Description

It looks like firefox cannot connect to the websocket while other browsers can.
I believe this issue has been present for a few months.
This issue seems to only present itself when starting the app multiple times (while developing). I have not been able to reproduce the issue when the app is run inside a docker container and the entire docker container is restarted / rebuilt between code changes.

The issue is also present when restarting the app multiple times inside a docker container without restarting the entire container (when using vscode devcontainers), indicating the issue is present on windows and linux(WSL).

Here is how I can produce the issue:

1. Write main.py
2. run it using python main.py

nicegui version: 1.4.18
windows 11
python 3.11.19

main.py:

from nicegui import ui

ui.button("click me!", on_click=lambda: ui.notify('clicked!'))

ui.run(
    port=80,
    title="test",
    favicon="🚀",
    reload=False,
    storage_secret="redacted",
    show=False,
    uvicorn_logging_level="debug",
)

Sometimes, Firefox reports error in the web developer tools:

Firefox can’t establish a connection to the server at ws://localhost/_nicegui_ws/socket.io/?client_id=5cd0b96f-d751-4877-b732-1bbabb013077&EIO=4&transport=websocket. socket.io.min.js:6:17426

The connection to ws://localhost/_nicegui_ws/socket.io/?client_id=5cd0b96f-d751-4877-b732-1bbabb013077&EIO=4&transport=websocket was interrupted while the page was loading. socket.io.min.js:6:17426

and the page refreshes periodically while showing sometimes:

1. a white page, or
2. the expected content but nothing happens when clicking things.

Firefox can connect again when in private browsing:

[kj4tmp]

the working browser shown above is Edge

[kj4tmp]

I suspect it has something to do with the browser cache.

[rodja]

Can anyone else reproduce this issue?

[kj4tmp]

it may require making small changes to the code (add / remove the button) between restarts to trigger the firefox failure

[me21]

Firefox works for me and my project. Probably one of the extensions interferes since the problem doesn't exist in private mode?.. 🤔
I start the app using Debug in PyCharm IDE.
If you suspect the cache is the issue, does reloading the page with Ctrl+F5 (bypassing the cache) help?

[kj4tmp]

I was not able to repeat the issue after re-installing the Adblock Ultimate Extension. I think I was running a multi-year old version of the extension.

[kj4tmp]

nevermind the issue is back.

Issue persists after:

1. Removing all extensions
2. ctrl + F5

[kj4tmp]

restarting firefox in "troubleshooting mode" also seems to fix the issue (from the hamburger menu -> help -> troubleshooting mode