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Failed to find app application: Heroku

Trying to deploy my dash plotly dashboard on Heroku but getting this error:

2020-02-12T20:06:28.207580+00:00 heroku[web.1]: Starting process with command `gunicorn app:server`
2020-02-12T20:06:34.455328+00:00 heroku[web.1]: State changed from starting to up
2020-02-12T20:07:03.644528+00:00 app[web.1]: WORKER TIMEOUT (pid:10)
2020-02-12T20:07:04.647635+00:00 app[web.1]: WORKER TIMEOUT (pid:11)
2020-02-12T20:07:15.625829+00:00 heroku[router]: at=error code=H12 desc="Request timeout" method=GET path="/" host=kalinaxchallenge.herokuapp.com request_id=f2e2ef3e-c454-45fc-a5f0-f3e4fa1f59e1 fwd="197.221.254.77" dyno=web.1 connect=1ms service=30000ms status=503 bytes=0 protocol=https
2020-02-12T20:07:22.939065+00:00 app[web.1]: Failed to find application: 'app'
2020-02-12T20:07:28.354927+00:00 app[web.1]: Failed to find application: 'app'
2020-02-12T20:07:29.073920+00:00 heroku[web.1]: State changed from up to crashed
2020-02-12T20:07:28.813680+00:00 heroku[router]: at=error code=H13 desc="Connection closed without response" method=GET path="/favicon.ico" host=kalinaxchallenge.herokuapp.com request_id=7c1977fe-5495-4327-990f-68a433ed2269 fwd="197.221.254.77" dyno=web.1 connect=1ms service=11173ms status=503 bytes=0 protocol=https
2020-02-12T20:07:29.059525+00:00 heroku[web.1]: Process exited with status 4

This is my app.json file:

{ “name”: “Dashboard”, “description”: “***", “repository”: "https://github.com/ / /” }

my procfile:

web: gunicorn app:server 

and my requirements.txt

dash_core_components==1.5.1
dash==1.6.1
dash_html_components==1.0.2
pandas==0.25.2
plotly==4.2.1
gunicorn==19.0.0
numpy==1.17.4

The app runs perfectly locally

Seems to be a weird error message, atleast to me because this is the structure of my project

Procfile
app.json
app.py
dataset1
dataset2
requirements.txt

I’m not sure why its failing to find the app application when its right there

You might have forgotten to add the following line, right after defining your app variable in app.py?

app = dash.Dash()
server = app.server # this should be added

gunicorn is looking for that, and it is possible that there is no server defined in your app.

Thank you so much! Was struggling with this error for a while now

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