Error¶

cannot import name 'dcc' from partially initialized module¶

cannot import name 'dcc' from partially initialized module 'dash' 
(most likely due to a circular import) (c:/.../dash.py)

One of the file is dash.py - should not name file dash.py as that would shadow the official dash module.

https://github.com/plotly/dash/issues/1889

Dash is running on http://127.0.0.1:8000/

 * Serving Flask app 'app'
 * Debug mode: on
No module named main

Solution: import the app in the main.py and then run it outside of the module/package app.run(host='127.0.0.1', port=8000, debug=True)

The SystemExit errorcode 3 is an exception thrown by werkzeug to trigger the reloade
To avoid having to do an extra step every time, you can pass "flask": true in the config, so this breakpoint is skipped

https://community.plotly.com/t/a-nonexistent-object-was-used-in-an-input-of-a-dash-callback-an-multipage-app/52007

in a multipage dashboard: https://stackoverflow.com/questions/71361010/a-nonexistent-object-was-used-in-an-input-of-a-dash-callback-an-multipage-app

Solution???

app.config['suppress_callback_exceptions'] = True

https://flask.palletsprojects.com/en/2.2.x/errorhandling/

https://code-maven.com/python-flask-catch-exception