404 Not Found: The requested URL was not found on the server

[bbinglongg]

Traceback (most recent call last):
File "E:\conda\env\data_formulator\lib\site-packages\flask\app.py", line 1511, in wsgi_app
response = self.full_dispatch_request()
File "E:\conda\env\data_formulator\lib\site-packages\flask\app.py", line 919, in full_dispatch_request
rv = self.handle_user_exception(e)
File "E:\conda\env\data_formulator\lib\site-packages\flask_cors\extension.py", line 194, in wrapped_function
return cors_after_request(app.make_response(f(*args, **kwargs)))
File "E:\conda\env\data_formulator\lib\site-packages\flask\app.py", line 802, in handle_user_exception
return self.handle_http_exception(e)
File "E:\conda\env\data_formulator\lib\site-packages\flask\app.py", line 777, in handle_http_exception
return self.ensure_sync(handler)(e) # type: ignore[no-any-return]
File "E:\workspace\data-formulator\py-src\data_formulator\app.py", line 260, in page_not_found
return send_from_directory(app.static_folder, "index.html") #'Hello 404!' #send_from_directory(app.static_folder, "index.html")
File "E:\conda\env\data_formulator\lib\site-packages\flask\helpers.py", line 565, in send_from_directory
return werkzeug.utils.send_from_directory( # type: ignore[return-value]
File "E:\conda\env\data_formulator\lib\site-packages\werkzeug\utils.py", line 575, in send_from_directory
raise NotFound()
werkzeug.exceptions.NotFound: 404 Not Found: The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again.