Issues with deploying python dash app on a web service

[harry1321]

I tried to deploy my dashboard on a web service which I had already try my dash app on my computer and it worked well. The web service is successfully built. However, there’s nothing showing on the web page. It gave me some errors:

dash.exceptions.NoLayoutException: The layout was None at the time that run_server was called.
Make sure to set the layout attribute of your application

I would also paste some files for anyone to help me locate where the error might be.
The web-service link：
https://traffic-dashboard.onrender.com

app.py

import dash
app = dash.Dash(__name__, suppress_callback_exceptions=True)
server = app.server

init.py

from app import app
from layouts import Layout
from callbacks import *

app.layout = Layout

if __name__ == '__main__':
    app.run_server(debug=False)

layouts.py

import pandas as pd
from dash import Dash, dcc, html
...
Layout = html.Div([side_bar,main_content],className = 'page')

I’m new to this tool, so any kind help would be great.
Sincerely,
Harry