[SOLVED] Flask does not run in debug mode: "Failed to import fsevents"

Flask does not run in debug mode: "Failed to import fsevents"

I have a simple app in Flask, not a lot more than "Hello, world" in it currently. flask run works great, but flask run --debug returns a warning.

/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/watchdog/observers/__init__.py:68: UserWarning: Failed to import fsevents. Fall back to kqueue
warnings.warn("Failed to import fsevents. Fall back to kqueue", stacklevel=1)

If I try to load the page, app does not work and internal server error occurs.

...
OSError: [Errno 24] Too many open files

macOS 15.5, python 3.12.7, flask 3.0.3.

Tried to include not only Flask, but MacFSEvents in requirements.txt, does not help. Any idea, what can be wrong?

Solution

Something was wrong with virtual environment, I deleted it and created once again, installed just Flask, and debug modes works fine. Problem solved.